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: [email protected] >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 -- [email protected] >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 -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
