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GPSMAP 76 vs. GPS V


Vertigo

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Lets put all other features aside and talk only about the antenna and signal.

 

I've heard all these great things about the GPS III and the Quad Helix antenna that it has, but frankly I really dont like the GPS. I'm only assumeing the GPS V has basicaly the same performance + WAAS

 

However, I noticed the GPS76 MAP also has a Quad Helix antenna built in. Does this mean it performs as good as the GPS V?

 

If not, then how much better will it be than my Etrex? I'm thinking about an upgrade.

 

[This message was edited by vertigo235 on March 24, 2002 at 08:51 PM.]

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I had both units but have recently sold the GPSMAP 76. I guess you can tell which one I liked better. icon_smile.gif

 

- It is my perception that the GPS V has the better reception of the two - but not by a heck of a lot.

 

- I like the backlight on the V more but the 76 has the larger screen...

 

- I find that the 76 and V fit equally well in a coat pocket. The V's form factor makes it nicer to use in the car and the turn-by-turn routing is also a huge plus.

 

- The firmware for the GPSMAP 76 has a lot more polish. The V's firmware is quite a bit quirkier and has more obvious bugs.

 

All things said, I'm really quite happy with the V and wouldn't trade it for anything currently on the market.

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I had both units but have recently sold the GPSMAP 76. I guess you can tell which one I liked better. icon_smile.gif

 

- It is my perception that the GPS V has the better reception of the two - but not by a heck of a lot.

 

- I like the backlight on the V more but the 76 has the larger screen...

 

- I find that the 76 and V fit equally well in a coat pocket. The V's form factor makes it nicer to use in the car and the turn-by-turn routing is also a huge plus.

 

- The firmware for the GPSMAP 76 has a lot more polish. The V's firmware is quite a bit quirkier and has more obvious bugs.

 

All things said, I'm really quite happy with the V and wouldn't trade it for anything currently on the market.

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Well, as I allready said. I really don't want to compare any other features, I just want to compare the reception.

 

The V is really too much money, I just want to compare with that one because the III+ doesn't have WAAS. I think it would be unfair to compare the 76 with the III+

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I have both & the V does receive the sats a little better than the MAP76 under certain conditions.My personal preference for caching is the MAP76 with the optional external antenna IF in a heavily wooded area where the external pulls in the sats a little better.I mainly use the V for road navigation. But in my experience,the MAP76 beats the eTrex series under any conditions. Others will disagree, for sure,but I have on many occasions taken out my eTrex Vista & the MAP76 side by side,in wooded areas, & the MAP76 held signal better every time, even without the external. The eTrex doesn't have the option for an external, either.I also have the III Plus & the eMap, & the MAP76 is the one I cache with. All this is from my experiences, & I'm sure you'll get other opinions.Hope it helps. icon_biggrin.gif

 

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I have both & the V does receive the sats a little better than the MAP76 under certain conditions.My personal preference for caching is the MAP76 with the optional external antenna IF in a heavily wooded area where the external pulls in the sats a little better.I mainly use the V for road navigation. But in my experience,the MAP76 beats the eTrex series under any conditions. Others will disagree, for sure,but I have on many occasions taken out my eTrex Vista & the MAP76 side by side,in wooded areas, & the MAP76 held signal better every time, even without the external. The eTrex doesn't have the option for an external, either.I also have the III Plus & the eMap, & the MAP76 is the one I cache with. All this is from my experiences, & I'm sure you'll get other opinions.Hope it helps. icon_biggrin.gif

 

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Antenna is a problem on the GPS Map76, it has to be as close to vertical as possible. I had bought the Map76, and found that if you tilt the GPS too much from vertical, the signal reception drops down to almost nothing. I returned the unit back at the store the next day. I bought the GPS V, and find that the display is alot easier to read. The Map76 that I had for a day had too much of a greenish tint to it, and the contrast adjustment did not help any. This is different from the Store's Display model, in that the Display was more readable, but I decided on getting the GPS V anyway.

 

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quote:
Originally posted by Geoffrey:

Antenna is a problem on the GPS Map76, it has to be as close to vertical as possible.


Geoffrey, I seriously doubt that this is the situation with the GPSmap76. I've tried to bring up the following point in previous threads, but I don't think anyone really knows the answer ... so let me just mention it again.

 

I believe that the quad-helix antenna in the GPS76/GPSmap76 series is oriented on its side. Observe the shape of the case at top of the unit. The antenna is situated above the battery holder. It is definitely NOT vertical! You would have to place the unit on its side the get the antenna pointing upward. So, whether you hold the case verical or flat out in front of you, shouldn't matter at all. (At least in theory!)

 

I speak from experience when I say that my older GPS12XL (patch antenna) seems to provide consistently better signal reception in poor coverage areas than my GPSmap76. Most of the time I can't get satellite lock with the GPSmap76 when placed on the dashboard in my car (either laying flat or tipped to the vertical), yet the GPS12XL (in any position) gets a 3D fix almost instantly!!!

 

Don't get me wrong ... I like the map76, it is very responsive in the field, has a better display, and has great features, including the mapping. I'd like to hear the experiences of others with regard to signal reception. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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With my experience with the 12XL I've noticed it's much less responsive than my eTrex. It has more lag when displaying signal reception, although it's about the same as the eTrex. Maybe this is what you're experieincing?

 

I can see almost everyone likes the GPS V. Maybe I'll just wait until I can afford one of those, even though I'm not too crazy about them or their prodecesors.

 

Keep the opinions comming!

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I dont see how this can be any worse than me having to hold my eTrex completely horizontal all the time. I've often wished I could hold it vertical actually icon_smile.gif

 

quote:
Originally posted by Geoffrey:

Antenna is a problem on the GPS Map76, it has to be as close to vertical as possible.


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I dont see how this can be any worse than me having to hold my eTrex completely horizontal all the time. I've often wished I could hold it vertical actually icon_smile.gif

 

quote:
Originally posted by Geoffrey:

Antenna is a problem on the GPS Map76, it has to be as close to vertical as possible.


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Rich, since you posted your question a few weeks ago I have played around with my GPSMAP76 at vertical and horizontal positions. First, my GPSr works fine mounted on the dash of my Tahoe. In the field my unit will pick up signals when its held in the horizontal position however, the signals increase when held vertically. The other day I was placing a cache in rather thick underbrush and as long as I kept moving with the unit held horizontally I did not lose the signal. Now, I am wondering with the 76S if you will have to hold it vertically while reading the compass. That will take a little getting used to.

 

Dave.

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quote:
Originally posted by Growley:

Rich, since you posted your question a few weeks ago I have played around with my GPSMAP76 at vertical and horizontal positions.


 

Dave, thanks for relating your experiences. You seem to get different results with your Map76 than I do. With mine, it doesn't seem to make much difference how it's oriented. When I'm in the field I am usually holding the unit near vertical and out in front of me as opposed holding it flat and close to me.

 

As far as the electronic compass, the ones I've seen had to be held parallel to the ground. I believe some of the newer ones have some sort of tilt compensation, but I don't know if the new Garmin unit possesses this feature. It's a good question!

 

Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by Rich in NEPA:

 

quote:

--------------------------------------------------------------------------------

Originally posted by Geoffrey:

Antenna is a problem on the GPS Map76, it has to be as close to vertical as possible.

--------------------------------------------------------------------------------

 

Geoffrey, I seriously doubt that this is the situation with the GPSmap76. I've tried to bring up the following point in previous threads, but I don't think anyone really knows the answer ... so let me just mention it again.

 

I believe that the quad-helix antenna in the GPS76/GPSmap76 series is oriented on its side. Observe the shape of the case at top of the unit. The antenna is situated above the battery holder. It is definitely NOT vertical!


 

I wondered about that, too, and then saw it confirmed in the GPSMap 76 manual. If you check out page 21 of the manual, you'll see an illustration of a hand holding the unit vertically. The caption reads, "When initializing the receiver or trying to receive satellite signals, orient the GPSMAP76 so the top of the unit points toward the sky. If the unit is held with the top of the unit pointed toward the horizon, satellite reception may be severely degraded."

 

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Moun10Bike, what sort of experiences have you had with your map76? How does it compare with other units you may have had, or have now? Where I am, I can receive the WAAS signal about 60% of the time but find that I get slightly different position fixes compared to the older 12XL. With WAAS disabled, the two units match nearly perfectly. I really like the map76's display and its configurability. The unit is a pleasure to use in the field. I'm just having a hard time learning to live with some of the signal reception quirks. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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Well I've given it all some thought and I think I've actually decided to buy the GPS V. Mainly because I really dont want to be disapointed again as I have been with the eTrex.

 

Another reason is that my dad has a Street Pilot and I'd really like to have many of the features it offers. The GPS V should do all this and more, I must admit the autorouteing is very exciting. Not to mention the extra memory space!

 

You only live once eh? Maybe this will finaly satisfy my GPS desires.

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From just my own, unscientific observations, I would place the GPSMap 76's reception somewhere between the Vista and the V. I have to confess, however, that I discovered the need to keep it vertically oriented well into my usage of it, and not long before I got the V, so that probably tainted my perception of its abilities. EraSeek has one as well and I believe that he has stated his belief that its reception underperforms his 12XL. (I had a 12XL a long time ago, but before SA was turned off, so I can't judge.)

 

I rarely get WAAS reception at most cache sites, so I have actually taken to turning it off most of the time unless I know that I'm going to be in wide open spaces. One reason that you might be getting the same position fixes with your two receivers with WAAS disabled, but different ones with it enabled, is that WAAS reception comes at the expense of "traditional" satellites if you are receiving a full complement of signals at your location. With WAAS off, your two receivers are likely picking up the same satellites; with it on, you are using two of your channels for the WAAS birds. This will result in different satellite geometry.

 

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Hmm, well I have to do a lot more comparison testing of the two. And I do plan on doing that when I get time. For the most part the 12 locks in quicker when started and usually gives a better EPE # for what that is worth. But the Map 76 keeps a signal much better in tough places where the 12 will lose reception. If I lay the 76 down on a log it will often lose the signal then. I have no poblem getting a signal with the 76 on the dash at a 45 degree angle. I usually keep WAAS enabled for no good reason. Waas usually fades in and out and does not seem to do that much for the Accuracy number. I have marked a position a number of times on top of NGS markers and the 76 is within a meter or two. I do want to test the unit more with and without WAAS and against the 12, but for the most part the 12 is tough and reliable, the 76 is fun and user friendly and holds a signal better.

 

"So I soon found my way back. Here. To the edge of the valley precipice, where the two worlds meet and intertwine, but ever so briefly, but ever so lightly, in a turbulent sort of way."

 

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Magellan 4000XL, ColorTrac, GPS 315

Garmin 3, 3plus, eMap, eTrex Vista, GPS Map76, GPS V.

 

Most of them had defects, and had to be exchanged, or returned. Only the Vista, and the GPS 3plus, were perfect in everyway, since they never had a glitch, and I could read the displays even when jogging a few miles.

 

Garmin GPS Map76:

The store only had one unit, and the one I had, had a LCD that was far greener that the store's display model. Just my bad luck with this one, since I must have picked a bad apple. I tried driving with it, and could never get the contrast adjustment right, so I could read it's display. I tried jogging a couple miles with it, and the GPS kept wigging out, when I angled it, so that i could see the readout clearly. If you stood it up vertically, it's Antenna would be vertical, behind the Garmin Logo.

gpsmap76Spic.jpg

 

Garmin GPS V:

According to Garmin Tech support and this messageboard, I must have picked a bad apple out of the basket of GPS V's. Since this unit kept freezing up while doing Autorouting, Requiring that I pop the battery door open, to unfreeze.

 

Other:

The GPS III had a short in the Basemap memory.

The ColorTrac had a defective case.

4000XL had a sluggish screen.

 

Too many bad apples for me

 

[This message was edited by Geoffrey on March 26, 2002 at 05:03 AM.]

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Wow, Geoffrey -- that's some bad luck!

 

Since 1995, I have owned these GPSRs (all Garmin):

 

  • GPS 40

  • GPS 12XL

  • GPS III

  • GPS III+

  • eTrex Vista

  • GPSMap 76

  • GPS V

 

The only issue that I've had is that something snapped on my GPS III+ when removing it from its mount after a motorcycle ride and the serial port stopped working (but that was fixed by Garmin within a couple of weeks). Everything else has been nearly flawless!

 

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quote:
Originally posted by Geoffrey:

If you stood it up vertically, it's Antenna would be vertical, behind the Garmin Logo.

 

gpsmap76Spic.jpg


 

Geoffrey, this is where I think you are wrong, and I'm not just trying to be argumentative. Look at the shape of the case just above the battery compartment (under the logo). The quadriliar antenna has the shape of an elongated cylinder. (Hence the shape of the movable antennas on the III+ and V, for example.) There is no way it can be aligned vertically in the map76. It has to be turned 90° on its side. Imagine a AA-size battery behind the logo that is parallel to the unit's own batteries.

 

The quad-helix (or guadrifilar) design was chosen as a compromise for better gain at the horizon. (Pic indicates typical radiation pattern.)

 

trad.gif

 

Now turn this diagram on its side. Can you see what I'm getting at? How does this configuration compare with the reception characteristics of both the typical patch antenna and the "vertically oriented" GPS-III+ and GPS-V antennas?

 

I guess this is what I'm most curious about. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by Rich in NEPA:

 

Geoffrey, this is where I think you are wrong, and I'm not just trying to be argumentative.


 

Rich, if you take a look at page 21 in the manual and observe the graphic, I think that you'll agree that Geoffrey is right. The caption reads:

 

"When initializing the receiver or trying to receive satellite signals, orient the GPSMAP76 so the top of the unit points toward the sky. If the unit is held with the top of the unit pointed toward the horizon, satellite reception may be severely degraded."

 

Although the graphic used doesn't show reference marks to indicate what plane it is being held in, I think that they would have used a different graphic (one that showed the buttons pointing skyward) and/or different terminology ("face" or "buttons" of the unit rather than "top" of the unit) if they meant that the receiver should be held parallel to the ground with the logo facing up.

 

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quote:
Originally posted by Moun10Bike:

Rich, if you take a look at page 21 in the manual and observe the graphic, I think that you'll agree that Geoffrey is right.


Mount10bike, I think we are having some difficulty getting on the same wavelength. icon_frown.gif I'm not questioning the issue of holding the unit in a vertical position (logo upward). What I'm trying to explain is that the antenna itself, physically, is NOT oriented to the vertical in side the case.

 

I realize that units with patch antennas should be held mostly with the logo facing upward, since the reception bias is perpendicular to the surface of the antenna. The reception bias of a quad-helix antenna is in a plane perpendicular to its axis. What I believe this means in the case of the 76/map76 receivers, is that the bias is not toward the horizon as would be the case with the III+/V, but in a plane that is 90° to the horizon (assuming you are holding the unit as recommended). Am I explaining this clearly? It's kinda frustrating.

 

(As an aside, I think we even have different User Manuals. My page 21 doesn't have a graphic showing how the unit should be oriented, only a screen shot of the Satellite Status display. The instructions are: "Turn the unit on and hold it in front of you with the top of the unit tilted upward." That's it. No other mention of how to hold the unit. Perhaps there is a newer version.)

 

Cheers ....

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by Moun10Bike:

Rich, if you take a look at page 21 in the manual and observe the graphic, I think that you'll agree that Geoffrey is right.


Mount10bike, I think we are having some difficulty getting on the same wavelength. icon_frown.gif I'm not questioning the issue of holding the unit in a vertical position (logo upward). What I'm trying to explain is that the antenna itself, physically, is NOT oriented to the vertical in side the case.

 

I realize that units with patch antennas should be held mostly with the logo facing upward, since the reception bias is perpendicular to the surface of the antenna. The reception bias of a quad-helix antenna is in a plane perpendicular to its axis. What I believe this means in the case of the 76/map76 receivers, is that the bias is not toward the horizon as would be the case with the III+/V, but in a plane that is 90° to the horizon (assuming you are holding the unit as recommended). Am I explaining this clearly? It's kinda frustrating.

 

(As an aside, I think we even have different User Manuals. My page 21 doesn't have a graphic showing how the unit should be oriented, only a screen shot of the Satellite Status display. The instructions are: "Turn the unit on and hold it in front of you with the top of the unit tilted upward." That's it. No other mention of how to hold the unit. Perhaps there is a newer version.)

 

Cheers ....

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by Rich in NEPA:

 

Mount10bike, I think we are having some difficulty getting on the same wavelength. icon_frown.gif I'm not questioning the issue of holding the unit in a vertical position (logo upward). What I'm trying to explain is that the antenna itself, physically, is NOT oriented to the vertical in side the case.


 

OK, I get you, Rich -- sorry for muddying the waters! I took your comment to Geoffrey stating that you "seriously doubt that this is the situation with the GPSmap76" when he mentioned that the GPSMap "has to be as close to vertical as possible" to mean that you disagreed with the evidence that the unit has to be held this way for best reception.

 

quote:

 

(As an aside, I think we even have different User Manuals.)


 

I'm using the latest manual posted to the Garmin site here.

 

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quote:
Originally posted by Rich in NEPA:

 

Mount10bike, I think we are having some difficulty getting on the same wavelength. icon_frown.gif I'm not questioning the issue of holding the unit in a vertical position (logo upward). What I'm trying to explain is that the antenna itself, physically, is NOT oriented to the vertical in side the case.


 

OK, I get you, Rich -- sorry for muddying the waters! I took your comment to Geoffrey stating that you "seriously doubt that this is the situation with the GPSmap76" when he mentioned that the GPSMap "has to be as close to vertical as possible" to mean that you disagreed with the evidence that the unit has to be held this way for best reception.

 

quote:

 

(As an aside, I think we even have different User Manuals.)


 

I'm using the latest manual posted to the Garmin site here.

 

24_700.gif

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quote:
Originally posted by Moun10Bike:

I took your comment to Geoffrey stating that you "seriously doubt that this is the situation with the GPSmap76" when he mentioned that the GPSMap "has to be as close to vertical as possible" to mean that you disagreed with the evidence that the unit has to be held this way for best reception.


 

I was afraid that my point was getting lost in the "translation." icon_biggrin.gif What I'm getting at may sound strange, but the only way I believe you can get the antenna itself in the 76/map76 in the vertical position is to flip the unit on its side (so that the logo is to the right or to the left, but still facing you).

 

I have to admit what surprises me most is that the issue of the 76/map76's unusual antenna design hasn't been a "hot topic" on this forum.

 

I think some of the problem with reception when the unit is held flat (as would be preferred with a patch antenna) is that the components inside the case would obscure a portion of the pattern. With the unit held vertically, these components are beneath the antenna toward the ground. I've noticed very little change in signal strength when shifted from vertical to flat so long as the unit is held further away from me.

 

I still need to experiment with turning the unit on its side (logo to right or left, facing me) so that that antenna is truly vertical (but I still wouldn't be sure which side the "top" of the antenna is at!) I certainly wouldn't want to use the unit in this manner, but I'm curious if this has much of an effect. What do you think?

 

Thanks for the link to the latest Manual. I'll be downloading the file for printing momentarily. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

 

[This message was edited by Rich in NEPA on March 26, 2002 at 10:44 AM.]

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quote:
Originally posted by Moun10Bike:

I took your comment to Geoffrey stating that you "seriously doubt that this is the situation with the GPSmap76" when he mentioned that the GPSMap "has to be as close to vertical as possible" to mean that you disagreed with the evidence that the unit has to be held this way for best reception.


 

I was afraid that my point was getting lost in the "translation." icon_biggrin.gif What I'm getting at may sound strange, but the only way I believe you can get the antenna itself in the 76/map76 in the vertical position is to flip the unit on its side (so that the logo is to the right or to the left, but still facing you).

 

I have to admit what surprises me most is that the issue of the 76/map76's unusual antenna design hasn't been a "hot topic" on this forum.

 

I think some of the problem with reception when the unit is held flat (as would be preferred with a patch antenna) is that the components inside the case would obscure a portion of the pattern. With the unit held vertically, these components are beneath the antenna toward the ground. I've noticed very little change in signal strength when shifted from vertical to flat so long as the unit is held further away from me.

 

I still need to experiment with turning the unit on its side (logo to right or left, facing me) so that that antenna is truly vertical (but I still wouldn't be sure which side the "top" of the antenna is at!) I certainly wouldn't want to use the unit in this manner, but I'm curious if this has much of an effect. What do you think?

 

Thanks for the link to the latest Manual. I'll be downloading the file for printing momentarily. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

 

[This message was edited by Rich in NEPA on March 26, 2002 at 10:44 AM.]

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I know what we need, Rich -- you should crack your unit open and confirm the antenna orientation for the rest of us! icon_biggrin.gif

 

I just sold my GPSMap 76, otherwise I would take it outside and experiement with holding it in different orientations to see how it receives. I think I am visualizing what you are suggesting -- that the linear antenna runs left to right under the logo, so that when you flip the unit on its side, it is vertical?

 

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I know what we need, Rich -- you should crack your unit open and confirm the antenna orientation for the rest of us! icon_biggrin.gif

 

I just sold my GPSMap 76, otherwise I would take it outside and experiement with holding it in different orientations to see how it receives. I think I am visualizing what you are suggesting -- that the linear antenna runs left to right under the logo, so that when you flip the unit on its side, it is vertical?

 

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quote:
Originally posted by Moun10Bike:

I know what we need, Rich -- you should crack your unit open and confirm the antenna orientation for the rest of us! icon_biggrin.gif


M10B, I think I'll pass on that experiment for now. icon_eek.gif But, it would be interesting to know what it looks like inside. I'm sure somebody out there has attempted to hack this unit.

 

quote:
I think I am visualizing what you are suggesting -- that the linear antenna runs left to right under the logo, so that when you flip the unit on its side, it is vertical?

Yes!!! That's exactly what I'm attempting to explain. I should have drawn a diagram and avoided most of the confusion. icon_wink.gif I can see that Garmin wanted to make the case design more elegant than the Magellan units which have that odd protrusion on the top where they put their quad-helix antenna. But, how does Garmin's decision affect the performance of that type of antenna? icon_confused.gif

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by Moun10Bike:

I know what we need, Rich -- you should crack your unit open and confirm the antenna orientation for the rest of us! icon_biggrin.gif


M10B, I think I'll pass on that experiment for now. icon_eek.gif But, it would be interesting to know what it looks like inside. I'm sure somebody out there has attempted to hack this unit.

 

quote:
I think I am visualizing what you are suggesting -- that the linear antenna runs left to right under the logo, so that when you flip the unit on its side, it is vertical?

Yes!!! That's exactly what I'm attempting to explain. I should have drawn a diagram and avoided most of the confusion. icon_wink.gif I can see that Garmin wanted to make the case design more elegant than the Magellan units which have that odd protrusion on the top where they put their quad-helix antenna. But, how does Garmin's decision affect the performance of that type of antenna? icon_confused.gif

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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An interesting thought, though I'm not convinced they didn't put it verticle on one side or the other. I've got a great idea...let's ask them. They've responded to me before..I'll give it a shot if their site isn't still down.

 

"And there on that lip, two currents did collide, one from below carrying up the fogs of the netherworld, and one from above carrying with it the mist of Valhalla."

 

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Rich; O.K. here are some very nonscientific results of a test I did yesterday. Before we begin there is a term I will use, "maxed out". Any signal that goes above the top line will be concidered maxed out. Lets begin. I took my GPSMAP76 outside in my yard (which does have some trees, however I was not standing under them)and let the unit get comfortable for about 15 minutes. Holding the GPSr in the vertical position I locked on to 8 birds; 5 were "maxed out" and 3 had lower signals but all the bars were black. I then held the GPSr at the horizontal position for approx. 5 minutes. I now remained locked on to 4 or 5 birds with 1 "maxed out", 2 or 3 in various lower signal levels and the rest of bars in a gray color. These signals continued to jump from bird to bird and I never lost signal. I then held the GPSr on its right side pointing to the right for approx. 5 minutes. I remained locked on 4 birds with 1 "maxed out" at all times. The other birds were lower signals however, all bars were black. Finally, I held the GPSr on its left side pointing to the left for approx. 5 minutes. I remained locked on to 4 or 5 birds at all times. More birds "maxed out" in this position than to the right. I would sometimes get 3 birds "maxed out" with the remaining birds showing a higher signal than when I held it to the right. SOOOO..In my opinion for my MAP76 vertical is best however, under limited canopy the horizontal position will work to quickly get through some brush without losing a signal. Holding it on the sides works but it is a very weird way of holding the unit.

Hope this adds to the overall confusion! icon_biggrin.gif

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Rich; O.K. here are some very nonscientific results of a test I did yesterday. Before we begin there is a term I will use, "maxed out". Any signal that goes above the top line will be concidered maxed out. Lets begin. I took my GPSMAP76 outside in my yard (which does have some trees, however I was not standing under them)and let the unit get comfortable for about 15 minutes. Holding the GPSr in the vertical position I locked on to 8 birds; 5 were "maxed out" and 3 had lower signals but all the bars were black. I then held the GPSr at the horizontal position for approx. 5 minutes. I now remained locked on to 4 or 5 birds with 1 "maxed out", 2 or 3 in various lower signal levels and the rest of bars in a gray color. These signals continued to jump from bird to bird and I never lost signal. I then held the GPSr on its right side pointing to the right for approx. 5 minutes. I remained locked on 4 birds with 1 "maxed out" at all times. The other birds were lower signals however, all bars were black. Finally, I held the GPSr on its left side pointing to the left for approx. 5 minutes. I remained locked on to 4 or 5 birds at all times. More birds "maxed out" in this position than to the right. I would sometimes get 3 birds "maxed out" with the remaining birds showing a higher signal than when I held it to the right. SOOOO..In my opinion for my MAP76 vertical is best however, under limited canopy the horizontal position will work to quickly get through some brush without losing a signal. Holding it on the sides works but it is a very weird way of holding the unit.

Hope this adds to the overall confusion! icon_biggrin.gif

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quote:
Originally posted by Growley:

Hope this adds to the overall confusion! icon_biggrin.gif


 

Growley, thanks for the effort you put into this. From your results it seems safe to suggest that the GPSmap76's antenna is indeed very directional. I've been searching the Web for similar discussions and haven't found anything to add to what we already know. For example, from Autonomous GPS Accuracy Report comes the following:

 

quote:

For example the Garmin 12XL manual shows the suggested orientation of the receiver which is about 25 degrees up from horizontal. The GPSMAP76 manual only suggests that the top of the unit be tilted upward. While in the open the GPSMAP76 works well with the unit tilted up about 40 degrees from horizontal, it performs terribly under canopy like this. The antenna is highly

directional, which can be seen by watching the satellite signal strength bars while rotating the receiver, and the above results were obtained by holding the receiver vertically. Interestingly enough, the 12XL performed the same either horizontally (actually up about 25 degrees) or vertically under the above conditions.


Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by Growley:

Hope this adds to the overall confusion! icon_biggrin.gif


 

Growley, thanks for the effort you put into this. From your results it seems safe to suggest that the GPSmap76's antenna is indeed very directional. I've been searching the Web for similar discussions and haven't found anything to add to what we already know. For example, from Autonomous GPS Accuracy Report comes the following:

 

quote:

For example the Garmin 12XL manual shows the suggested orientation of the receiver which is about 25 degrees up from horizontal. The GPSMAP76 manual only suggests that the top of the unit be tilted upward. While in the open the GPSMAP76 works well with the unit tilted up about 40 degrees from horizontal, it performs terribly under canopy like this. The antenna is highly

directional, which can be seen by watching the satellite signal strength bars while rotating the receiver, and the above results were obtained by holding the receiver vertically. Interestingly enough, the 12XL performed the same either horizontally (actually up about 25 degrees) or vertically under the above conditions.


Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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I believe I've read that same report, and seen another that shows when held vertically the Map 76 pretty well outperforms several other units in averaged accuracy.

 

Anyway..

 

I've got a reply fom Garmin. My question is at the bottom:

 

Thank you for contacting Garmin.

 

This unit features a built-in quad helix antenna for superior reception and can provide position accuracy to less than three meters when receiving WAAS http://www.garmin.com/aboutGPS/waas.html corrections. The antenna is under the Garmin logo.

 

Thank you and best Regards,

 

Frank Brzozowski

Product Support Specialist

 

GARMIN International

 

 

Problem: Not a problem, just wish to know how the antenae is situated in the Map76 unit. Is it verticle on one side, or does it lay left to right across the unit where the logo is?

 

So it looks as if maybe you were right.

 

2573_200.jpg

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Yeah, he does not really answer the question, but maybe avoids it. I'll try again. As far as how to hold it, it is clear to me in all I've read that it is highly directional and should be held as vertical as possible. Even if the antennae is laid on it's side across the top it would not make sense to hold it sidways as it seems to me that the unit itself would then bock some of the signal.

 

2573_200.jpg

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quote:
Originally posted by vertigo235:

The answer apears to be Vertical, not on it's side.


Why is it that some people have to read things into a post that isn't there?! icon_rolleyes.gif Geez ... Vertigo, we know that you're supposed to hold it upright and not on it's side. Please read the posts more carefully. Thank you. icon_wink.gif (I'm only teasing you.)

 

However, the question is in regards to the physical orientation of the antenna inside the unit. A quadrifilar antenna is cylindrical in shape, about the size of a AA battery. It appears the only way that Garmin could stuff one into the map76's case is to lay it on its side, parallel to the two batteries, and within the bulging section under the logo.

 

Since quadrifilar antennas are designed to operate in a vertical orientation (like a smokestack), the question becomes how does the Garmin configuration affect the performance of such an antenna?

 

BTW, EraSeek, the reply you got from Garmin doesn't surprise me. It's as if they didn't even bother to read your message! Thanks for trying. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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quote:
Originally posted by vertigo235:

The answer apears to be Vertical, not on it's side.


Why is it that some people have to read things into a post that isn't there?! icon_rolleyes.gif Geez ... Vertigo, we know that you're supposed to hold it upright and not on it's side. Please read the posts more carefully. Thank you. icon_wink.gif (I'm only teasing you.)

 

However, the question is in regards to the physical orientation of the antenna inside the unit. A quadrifilar antenna is cylindrical in shape, about the size of a AA battery. It appears the only way that Garmin could stuff one into the map76's case is to lay it on its side, parallel to the two batteries, and within the bulging section under the logo.

 

Since quadrifilar antennas are designed to operate in a vertical orientation (like a smokestack), the question becomes how does the Garmin configuration affect the performance of such an antenna?

 

BTW, EraSeek, the reply you got from Garmin doesn't surprise me. It's as if they didn't even bother to read your message! Thanks for trying. Cheers ...

 

~Rich in NEPA~

 

1132_1200.jpg

 

=== A man with a GPS receiver knows where he is; a man with two GPS receivers is never sure. ===

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Ok I did a little test tonite too. I headed down to the Sound where there is good western exposure, where I've seen a suveror(sp?) taking readings with a GPS unit. I found the mark, but unfortunately it is not a monumented mark so I can not confirm the actual coords, but I used the mark to take relative readings anyway. Here's what I did.

----

Simple mark with Map76 WAAS enabled and "D's" across the board.

 

Map 76 WAAS enabled averaged for 1 min (I have no patience)

 

Map 76 no WAAS

 

Map76 No WAAS averaged 1 min

 

Garmin 12

 

Garmin 12 averaged on minute

----

Here what I got using the "Map 76 WAAS enabled averaged 1 min" poition as a basis.

----

Map 76 WAAS position was 1 meter west &1 meter north

 

Map 76 no WAAS was dead on

 

Map76 no WAAS averaged 1 min was 1 meter North

 

Garmin 12 was 2 meters East & 3 meters North

 

Garmin 12 averaged for 1 min was 2 meters East and 2 meters North

----

 

Looks like the biggest difference is between the 76 and the 12 readings.

 

2573_200.jpg

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dadgum, this discussion got deep quick. This is my opinion. It's just that. I didn't even get up from my desk to form it. The V has a better antanae. It's removable and you can remote mount an option antanii (I'll spell that word differently every time till I get one right). Because you can twist the thing to whatever direction you need based on how you are holding the V it will get better reception in general than the MAP. So what does that mean? Nothing really. The difference for all intents and purposes most of us won't use, or notice. Under dense canopy maybe it would matter quite a bit. So there you go. Buy whatever unit you want. You have a beter antanai either way than an eTrex. You can base your decision on features and not worry about the antenea.

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