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Cellular forums Home > Archive > Garmin GPS > January 2008 > 52 channel recivers
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52 channel recivers
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| Chull 2008-01-16, 10:33 pm |
| Is it a safe assumption that a 52 channel receiver will be more sensitive
than a 12 channel.
(I'm also assuming that Channels = number of satellites it can receive
information from at the same time.)
When Garmin say High-sensitivity receiver... is that an indication and/or a
result of the number of satellites it can receive information from at the
same time?
I have an Older GPSMAP 76CS (non secure digital card) and have problems
going thru the woods and losing the signal while snowmobiling. It then takes
longer than I would like to reacquire a signals when I get out of the woods.
According to my &^CS I have gone 440 mph on my snowmobile! Over 200 mph
often!
Thanks for the help
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| Chull 2008-01-16, 10:33 pm |
| 52 = 51.
The nestest one I'm looking at is a 51 satellite receiver.
Sensitivity: Aquisition 146 dBm; Tracking 158 dBm
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| Carl Heinz 2008-01-16, 10:33 pm |
| On Wed, 16 Jan 2008 18:55:01 -0500, "Chull" <chull001@rochester.rr.Not
Needed.com> wrote:
>Is it a safe assumption that a 52 channel receiver will be more sensitive
>than a 12 channel.
>(I'm also assuming that Channels = number of satellites it can receive
>information from at the same time.)
>When Garmin say High-sensitivity receiver... is that an indication and/or a
>result of the number of satellites it can receive information from at the
>same time?
>
>I have an Older GPSMAP 76CS (non secure digital card) and have problems
>going thru the woods and losing the signal while snowmobiling. It then takes
>longer than I would like to reacquire a signals when I get out of the woods.
>According to my &^CS I have gone 440 mph on my snowmobile! Over 200 mph
>often!
>
>Thanks for the help
>
Don't know about 52 channels, but the 76CSx uses SiRF and I can get satellites
inside the house with a 76Cx.
--
Carl Heinz
cfheinz57@charter.net
(Remove number)
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| Xandros Desktop OS User 2008-01-16, 10:33 pm |
| Carl Heinz wrote:
> On Wed, 16 Jan 2008 18:55:01 -0500, "Chull" <chull001@rochester.rr.Not
> Needed.com> wrote:
>
>
>
> Don't know about 52 channels, but the 76CSx uses SiRF and I can get satellites
> inside the house with a 76Cx.
1. SiRF3 chip receivers fantastic. Appears to even record reflected
signal ( satellites behind my building!).
2. 52 channel. Am I missing something? I thought there were only 24
active US NAVSTAR satellites at any one time. Sounds like a 200mph car
when the speed limit is 55mph!
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| Happy Trails 2008-01-17, 4:34 am |
| On Thu, 17 Jan 2008 12:41:36 +1030, Xandros Desktop OS User
<Tony42Adel@yahoo.com> wrote:
>2. 52 channel. Am I missing something?
Yes, son, you are missing quite a few things I'm afraid.
Firstly, the system provides for 32 active satellites at any one time,
and I believe there is just about that number active right now. There
is a 5-bit field available in the gps message structure for the SV
number. Two to the power of 5 is 32. There are spares, also, but
more than 32 cannot be tracked simulaneously in the GPS system.
Next, each satellite is capable of transmitting on more than one
frequency. To track each frequency a channel is needed. RTK (high
precision) GPS needs to track the L1 and L2 frequencies from 5 or more
satellites to work.
Thirdly, there is a growing number of satellite navigation systems to
choose from. Some receiver manufacturers are looking forward to the
day when you have a full complement of satellites from Navstar-GPS,
Glonass, Galileo, and maybe even the Chinese Beidou system to track
simultaneously. How many channels would that take?
And that doesn't even cover the additional military frequencies!
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| Hey - Thank you all for the info - Helpful!!
This http://www.proporta.com/F02/PPF02P0...3782&t_mode=des is what I
have been looking at as the display size on my old 76CS does not provide
enough 'context' in many situations.
But then I would have to find a PDA that will run nRoute! : )
Spending the money Never Ends!!
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"Happy Trails" <nomail@myplace.com> wrote in message
news:hc6vo39grfci6si
2cknp2vpnarddf3ue1p@
4ax.com...
> On Thu, 17 Jan 2008 12:41:36 +1030, Xandros Desktop OS User
> <Tony42Adel@yahoo.com> wrote:
>
> Yes, son, you are missing quite a few things I'm afraid.
>
> Firstly, the system provides for 32 active satellites at any one time,
> and I believe there is just about that number active right now. There
> is a 5-bit field available in the gps message structure for the SV
> number. Two to the power of 5 is 32. There are spares, also, but
> more than 32 cannot be tracked simulaneously in the GPS system.
>
> Next, each satellite is capable of transmitting on more than one
> frequency. To track each frequency a channel is needed. RTK (high
> precision) GPS needs to track the L1 and L2 frequencies from 5 or more
> satellites to work.
>
> Thirdly, there is a growing number of satellite navigation systems to
> choose from. Some receiver manufacturers are looking forward to the
> day when you have a full complement of satellites from Navstar-GPS,
> Glonass, Galileo, and maybe even the Chinese Beidou system to track
> simultaneously. How many channels would that take?
>
> And that doesn't even cover the additional military frequencies!
>
This is not correct. The satellite ID field is 6 bits. Some of the IDs are
used
for special purposes, for example ID 0 is a "dummy" satellite, presumably
for
testing purposes. And some of the IDs are used to identify certain data
pages
so may not be available as real satellite IDs.
I'm not exactly certain but I think the WAAS satellites use some of the
reserved IDs from 33-50 or so. So my guess is that a "52" channel GPS
receiver means that it can receive the 32 standard satellites and 20 more
satellites that would be some kind of GPS augmentation, e.g. WAAS or EGNOS.
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| newshound 2008-01-19, 4:33 am |
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> When Garmin say High-sensitivity receiver... is that an indication and/or
> a
> result of the number of satellites it can receive information from at the
> same time?
In practical terms, the Etrex H still works in woods and narrow valleys
where the older Etrex will lose signal. I'm very impressed by the
improvement.
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