Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
Hi David, [] I have two 1804Ms with 6channel trimble boards and one with 8-channel. The 8-channel one will occasionally emit an 8-channel message. Most often at bootup. -- Björn Thanks, Björn. Do you mean that the 6-channel board will occasionally emit 8-channel messages at boot-up? Tack. David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
Hi David, >> Ah, I didn't realize this was based on the Trimble board - I was >> having a mental seizure and thinking it was using a Motorola OnCore, >> as so many of the others did. Are you really sure it is an SV6? >> Trimble also made an SV8 timing that was in the same form factor and >> if it was using that it would certainly explain why you sometimes see >> more than 6 satellites - although I have a vague memory that if you >> talk to it as if it was a 6-channel board it starts pretending to be >> one for reasons of backwards compatibility, so even if you do have the >> SV8 in there it likely won't do you much good. > > Next time I have the unit open I will take a look. Are there obvious > markings to distinguish the boards (it's a board and not a box), as I > recall looking but no seeing any. I have two 1804Ms with 6channel trimble boards and one with 8-channel. The 8-channel one will occasionally emit an 8-channel message. Most often at bootup. -- Björn ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
> Next time I have the unit open I will take a look. Are there obvious > markings to distinguish the boards (it's a board and not a box), as I recall > looking but no seeing any. It's been a while, but from what I remember the boards look almost identical - the standard configuration has a part of 9-pin D-Types, an SMB connector for the antenna and a 3-pin header for the power. Probably the best thing to do is to look for the P/N and google it. Those older units seem to have fallen into the memory hole at Trimble, though - they don't quite deny ever making them, but seem to have almost no info on them now. I have had a look on my external hard drive that's got all the old crap backed up on it, but came up blank - that doesn't mean it's not there, just that my "filing" system has failed :) Regards, Pete ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
So easily a 20 dB shortfall. I will look out for a similar antenna. Thanks On 11/2/2011 5:01 PM, Robin Kimberley wrote: The ET6000 used Trimble Bullet antennae when I was selling them in the UK. I seem to remember about 35db of gain in that antenna. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Joe Leikhim Sent: 02 November 2011 18:52 To: time-nuts@febo.com Subject: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit I tried a similar Garmin antenna with my Datum ET6000 and the lock times were really long, even with the antenna on a 14 foot pole above the roof. I attribute a lot of this to the long 8 ft RG174 style coax pigtail. I have to wonder if the gain of the preamp as published actually includes the inherent cable loss, and even if so the preamp must be screaming in gain to make up for the loss. I intend to get a proper antenna. Here is a comparison of specs of these type antennas: http://gpsinformation.net/main/gpsantrev1.htm -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida www.Leikhim.com jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.1834 / Virus Database: 2092/4591 - Release Date: 11/02/11 -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida www.Leikhim.com jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
The ET6000 used Trimble Bullet antennae when I was selling them in the UK. I seem to remember about 35db of gain in that antenna. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Joe Leikhim Sent: 02 November 2011 18:52 To: time-nuts@febo.com Subject: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit I tried a similar Garmin antenna with my Datum ET6000 and the lock times were really long, even with the antenna on a 14 foot pole above the roof. I attribute a lot of this to the long 8 ft RG174 style coax pigtail. I have to wonder if the gain of the preamp as published actually includes the inherent cable loss, and even if so the preamp must be screaming in gain to make up for the loss. I intend to get a proper antenna. Here is a comparison of specs of these type antennas: http://gpsinformation.net/main/gpsantrev1.htm -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida www.Leikhim.com jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ 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. ___ 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.
[time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
I tried a similar Garmin antenna with my Datum ET6000 and the lock times were really long, even with the antenna on a 14 foot pole above the roof. I attribute a lot of this to the long 8 ft RG174 style coax pigtail. I have to wonder if the gain of the preamp as published actually includes the inherent cable loss, and even if so the preamp must be screaming in gain to make up for the loss. I intend to get a proper antenna. Here is a comparison of specs of these type antennas: http://gpsinformation.net/main/gpsantrev1.htm -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida www.Leikhim.com jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
By the way, this doesn't mean that the GA-27 is a poor antenna design, it's just not the best antenna choice for this situation. The GA-27 is intended as an external antenna for Garmin's handheld receivers, which normally operate with passive patch or helix antennas. So the receiver itself needs to be sensitive enough to work well when an unamplified antenna is connected directly to the receiver, and the GA-27 preamp only needs to provide enough gain to overcome the losses in the cable plus a bit more. Additional gain could be detrimental in some circumstances (e.g. when placed near transmitting antennas on a vehicle), so the GA-27 might well be the best antenna for the Garmin handheld receivers. But a GPS board module is intended to be built into some piece of equipment, and probably expected to always be fed from a remote amplified antenna, never a local passive antenna. In those circumstances, it makes sense to put all the necessary gain at the antenna preamp and let the receiver be less sensitive. The manufacturer will recommend some antenna for use with the receiver, and though you don't usually have to use that particular antenna, it's probably a good idea for your antenna/cable/splitter setup to provide roughly the same signal level at the receiver. - Dave On Wed, Nov 2, 2011 at 01:19, David J Taylor wrote: >> I've made a small Web page describing what happened when I changed the >> puck antenna on a Rapco 1804M for a more sensitive one. The Rapco 1804M >> expects a big outside antenna. >> >> http://www.satsignal.eu/ntp/Rapco-1804M-notes.html > > This page has now been updated to provide a comparison between three puck > antennas - the Garmin GA 27 (BNC), a 3rd-party low-cost puck, and a Gilsson > puck antenna. It seems that the even higher signal level from the Gilsson > benefits the 1804M more than the other two. > > Cheers, > David > -- ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
Ah, I didn't realize this was based on the Trimble board - I was having a mental seizure and thinking it was using a Motorola OnCore, as so many of the others did. Are you really sure it is an SV6? Trimble also made an SV8 timing that was in the same form factor and if it was using that it would certainly explain why you sometimes see more than 6 satellites - although I have a vague memory that if you talk to it as if it was a 6-channel board it starts pretending to be one for reasons of backwards compatibility, so even if you do have the SV8 in there it likely won't do you much good. Next time I have the unit open I will take a look. Are there obvious markings to distinguish the boards (it's a board and not a box), as I recall looking but no seeing any. As the unit is only required for frequency, I am not intending to modify it. It has OCXO with quite good specifications, so it will more than meet my needs. It would likely meet my needs five minutes after being switched on! True, but this is time-nuts. The pursuit of more accuracy than you need is the whole purpose of the list :) Regards, Pete Yes, I know! Sad, but 10 Hz at 150 MHz and PCs to within a few microseconds will do me nicely! Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
> Yes, that in consistent with what I'm seeing, Pete, thanks. I am told that > the actual receiver is a Trimble SVeeSix, so why I occasionally see eight > reports from the Rapco firmware I don't understand. Ah, I didn't realize this was based on the Trimble board - I was having a mental seizure and thinking it was using a Motorola OnCore, as so many of the others did. Are you really sure it is an SV6? Trimble also made an SV8 timing that was in the same form factor and if it was using that it would certainly explain why you sometimes see more than 6 satellites - although I have a vague memory that if you talk to it as if it was a 6-channel board it starts pretending to be one for reasons of backwards compatibility, so even if you do have the SV8 in there it likely won't do you much good. > As the unit is only required for frequency, I am not intending to modify it. > It has OCXO with quite good specifications, so it will more than meet my > needs. It would likely meet my needs five minutes after being switched on! True, but this is time-nuts. The pursuit of more accuracy than you need is the whole purpose of the list :) Regards, Pete ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
Assuming it's using a timing-optimized receiver, the lack of a clear view to the sky is probably the biggest problem. Once they have a valid almanac, they will normally select the satellites with the highest elevation angles - and if you have an obstructed view that might well include several that are not visible. Obviously, the less channels on the receiver, the bigger an issue this is - on top of this, the timing receivers tend to be engineered to favor selectivity over sensitivity (the idea being that the gain is in the antenna and you can select it to match the cable losses). Yes, that in consistent with what I'm seeing, Pete, thanks. I am told that the actual receiver is a Trimble SVeeSix, so why I occasionally see eight reports from the Rapco firmware I don't understand. I have no idea if the firmware in the Rapco will support the 8-channel UT+ - but the fact that the monitoring software seems to have spaces for up to 8 SVs gives me some hope it might (or possibly there is some later FW that does). This could be worth trying. Regards, Pete Bell As the unit is only required for frequency, I am not intending to modify it. It has OCXO with quite good specifications, so it will more than meet my needs. It would likely meet my needs five minutes after being switched on! Thanks for your comments. I've updated the Web page about the 6/8 channels, and added a couple of pointers for those who might want to try the antennas. An outside one with a clear sky view would like be better than any of these puck antennas. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
Assuming it's using a timing-optimized receiver, the lack of a clear view to the sky is probably the biggest problem. Once they have a valid almanac, they will normally select the satellites with the highest elevation angles - and if you have an obstructed view that might well include several that are not visible. Obviously, the less channels on the receiver, the bigger an issue this is - on top of this, the timing receivers tend to be engineered to favor selectivity over sensitivity (the idea being that the gain is in the antenna and you can select it to match the cable losses). I have no idea if the firmware in the Rapco will support the 8-channel UT+ - but the fact that the monitoring software seems to have spaces for up to 8 SVs gives me some hope it might (or possibly there is some later FW that does). This could be worth trying. Regards, Pete Bell On Wed, Nov 2, 2011 at 4:19 PM, David J Taylor wrote: >> I've made a small Web page describing what happened when I changed the >> puck antenna on a Rapco 1804M for a more sensitive one. The Rapco 1804M >> expects a big outside antenna. >> >> http://www.satsignal.eu/ntp/Rapco-1804M-notes.html > > This page has now been updated to provide a comparison between three puck > antennas - the Garmin GA 27 (BNC), a 3rd-party low-cost puck, and a Gilsson > puck antenna. It seems that the even higher signal level from the Gilsson > benefits the 1804M more than the other two. > > Cheers, > David > -- > SatSignal software - quality software written to your requirements > Web: http://www.satsignal.eu > Email: david-tay...@blueyonder.co.uk > > ___ > 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. > ___ 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.
Re: [time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
I've made a small Web page describing what happened when I changed the puck antenna on a Rapco 1804M for a more sensitive one. The Rapco 1804M expects a big outside antenna. http://www.satsignal.eu/ntp/Rapco-1804M-notes.html This page has now been updated to provide a comparison between three puck antennas - the Garmin GA 27 (BNC), a 3rd-party low-cost puck, and a Gilsson puck antenna. It seems that the even higher signal level from the Gilsson benefits the 1804M more than the other two. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
[time-nuts] Monitoring the Rapco 1804M - how antenna changes affect the unit
Folks, I've made a small Web page describing what happened when I changed the puck antenna on a Rapco 1804M for a more sensitive one. The Rapco 1804M expects a big outside antenna. http://www.satsignal.eu/ntp/Rapco-1804M-notes.html Simply, the better signal provided a more consistent lock. I was slightly surprised by this, as I had assumed that any modern puck antenna would probably be similar in signal-to-noise to any other low-cost puck antenna, and that the SNR (and hence quality) would be fixed by the puck rather than the main receiver. However, it seems that in this case, the built-in Trimble SVeeSix module actually needs a fair whack of signal coming in. I expect most of you already knew that! I have another puck to try when an MCX to N-type adapter arrives from China It also demonstrated to me why 12 channels would be better than six, as the Trimble RX doesn't seem to learn that my best view is south, and it keeps looking for satellites in the "wrong" part of the sky. It doesn't seem to recognise that when there is one channel's satellite with no signal, it could use that one channel to go and look for other satellites. 12 channels would give it a higher chance of 5 good signals. I've included a download of the programs I have developed to capture and analyse the data. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
