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Re: [time-nuts] AMU vs dBc

Didier Juges

Mon, Nov 23, 2009 10:58 PM

How about Arithmetically Meaningless Units?

Didier

------Original Message------
From: Tom Van Baak
Sender: time-nuts-bounces@febo.com
To: Time-Nuts
ReplyTo: Tom Van Baak
ReplyTo: Time-Nuts
Subject: Re: [time-nuts] AMU vs dBc
Sent: Nov 23, 2009 4:05 PM

A quick play with Gnumerics gave me the formula dBc = 20*log10(AMU)+25,5
to have the best match, and RMS error of 2,23 where as the dBc = AMU +
33,9 has the RMS error of 4,34.

AMU
Arbitrary Manufacturer Units
Antenna Measurement Units
Arbitrary Mystery Units

See if these help your estimate:

http://gauss.gge.unb.ca/papers.pdf/SNR.memo.pdf
ftp://goes.gsfc.nasa.gov/pub/chesters/goesref/Moreau_GPS.pdf
http://www.wavedigm.com/pdf/UG_smartGPS.pdf

/tvb

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How about Arithmetically Meaningless Units? Didier ------Original Message------ From: Tom Van Baak Sender: time-nuts-bounces@febo.com To: Time-Nuts ReplyTo: Tom Van Baak ReplyTo: Time-Nuts Subject: Re: [time-nuts] AMU vs dBc Sent: Nov 23, 2009 4:05 PM > A quick play with Gnumerics gave me the formula dBc = 20*log10(AMU)+25,5 > to have the best match, and RMS error of 2,23 where as the dBc = AMU + > 33,9 has the RMS error of 4,34. AMU Arbitrary Manufacturer Units Antenna Measurement Units Arbitrary Mystery Units See if these help your estimate: http://gauss.gge.unb.ca/papers.pdf/SNR.memo.pdf ftp://goes.gsfc.nasa.gov/pub/chesters/goesref/Moreau_GPS.pdf http://www.wavedigm.com/pdf/UG_smartGPS.pdf /tvb _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ------------------------ Sent from my BlackBerry Wireless thingy while I do other things...

Arnold Tibus

Mon, Nov 23, 2009 11:33 PM

Hi everybody,

in a document from Trimble
(TTM637VME/TTM357VXI
GPS Satellite Receiver
Addendum, User's Guide)
I found:

"The signal level (Byte 5) is a linear approximation of C/N0 which is stated in antenna amplitude
measurement units (AMUs), a Trimble devised unit. An approximate correlation of AMU
levels to C/N0 follows:
5 AMUs -20 dB SNR
16 AMUs -10 dB SNR or AMUs 51 *
26 AMUs -5 dB SNR

The C/N0 is affected by five basic parameters:

Signal strength from the GPS satellite.
Receiver/antenna gain.
Pre-amplifier noise figure.
Receiver noise bandwidth.
Accumulator sample rate and statistics.
The approximation is very accurate from 0 to 25 AMUs"

In TBoltMon under 'Packet Masks and Options'/
'Aux Byte (3)'/ 'Output dBc/Hz' you can set what
kind of readout you want to see under 'AMU'
I have it set always to 'dBc/Hz and most of the
Satellites are coming in with up to 45 dBc/Hz.

A quick check (not easy because these beasts dont stop
moving ;-) ) gives about the following values in AMU / dBc/Hz:

2 / 29
5 / 36
5.5 / 39
6.2 / 40
7 / 41
9 / 43
10 / 44
11 / 45

good luck,
cheers

Arnold

On Mon, 23 Nov 2009 22:58:53 +0000, Didier Juges wrote:

How about Arithmetically Meaningless Units?

Didier

A quick play with Gnumerics gave me the formula dBc = 20*log10(AMU)+25,5
to have the best match, and RMS error of 2,23 where as the dBc = AMU +
33,9 has the RMS error of 4,34.

AMU
Arbitrary Manufacturer Units
Antenna Measurement Units
Arbitrary Mystery Units

See if these help your estimate:

http://gauss.gge.unb.ca/papers.pdf/SNR.memo.pdf
ftp://goes.gsfc.nasa.gov/pub/chesters/goesref/Moreau_GPS.pdf
http://www.wavedigm.com/pdf/UG_smartGPS.pdf

/tvb

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------------------------ Sent from my BlackBerry Wireless thingy while I do other things...

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Hi everybody, in a document from Trimble (TTM637VME/TTM357VXI GPS Satellite Receiver Addendum, User's Guide) I found: "The signal level (Byte 5) is a linear approximation of C/N0 which is stated in antenna amplitude measurement units (AMUs), a Trimble devised unit. An approximate correlation of AMU levels to C/N0 follows: 5 AMUs -20 dB SNR 16 AMUs -10 dB SNR or AMUs 51 * 26 AMUs -5 dB SNR The C/N0 is affected by five basic parameters: 1. Signal strength from the GPS satellite. 2. Receiver/antenna gain. 3. Pre-amplifier noise figure. 4. Receiver noise bandwidth. 5. Accumulator sample rate and statistics. The approximation is very accurate from 0 to 25 AMUs" In TBoltMon under 'Packet Masks and Options'/ 'Aux Byte (3)'/ 'Output dBc/Hz' you can set what kind of readout you want to see under 'AMU' I have it set always to 'dBc/Hz and most of the Satellites are coming in with up to 45 dBc/Hz. A quick check (not easy because these beasts dont stop moving ;-) ) gives about the following values in AMU / dBc/Hz: 2 / 29 5 / 36 5.5 / 39 6.2 / 40 7 / 41 9 / 43 10 / 44 11 / 45 good luck, cheers Arnold On Mon, 23 Nov 2009 22:58:53 +0000, Didier Juges wrote: >How about Arithmetically Meaningless Units? >Didier >------Original Message------ >From: Tom Van Baak >Sender: time-nuts-bounces@febo.com >To: Time-Nuts >ReplyTo: Tom Van Baak >ReplyTo: Time-Nuts >Subject: Re: [time-nuts] AMU vs dBc >Sent: Nov 23, 2009 4:05 PM >> A quick play with Gnumerics gave me the formula dBc = 20*log10(AMU)+25,5 >> to have the best match, and RMS error of 2,23 where as the dBc = AMU + >> 33,9 has the RMS error of 4,34. >AMU >Arbitrary Manufacturer Units >Antenna Measurement Units >Arbitrary Mystery Units >See if these help your estimate: >http://gauss.gge.unb.ca/papers.pdf/SNR.memo.pdf >ftp://goes.gsfc.nasa.gov/pub/chesters/goesref/Moreau_GPS.pdf >http://www.wavedigm.com/pdf/UG_smartGPS.pdf >/tvb >_______________________________________________ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. >------------------------ Sent from my BlackBerry Wireless thingy while I do other things... >_______________________________________________ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there.