From a limited experience last Saturday night (02.027 0400 UTC start), I've found that ProMark 2 may not be up for cool weather/long session work, such as what's intended this Saturday night for the Interstate ORGI experiment. First, and foremost, 3 hours and 42 minutes on a fresh set of Energizer alkaline batteries (temperature around 36-40°) was less than desireable. Second problem is making the Saturday night ephemeris thing work with multiple CORS stations. Strange thing, 2 of my five CORS stations came in with the requested data of 4 hours (between 10:00 p.m. cst and 02:00 a.m. cst - 0400-0800 utc). Three of the CORS stations refuse to cooperate. I imagine Phil can answer this, but I don't think the battery situation will allow much more. The data I was able to analyze looked extremely good, even with as little as one hour of simultaneous PM2 to CORS data. Even had several fixed solutions, just not enough time for mega-vectors.

I'll be running two Locus units anyway, but I do think the ProMark2 on any night other than Saturday, and better power supply, would out perform the Locus units.

J.D. Billings

J.D.

You might try Lithium batteries as they stand up in the cold better then the alkaline but they are pretty expensive.

I guess we will all have to patry Saturday nights instead of making GPS observations.

Thanks for keeping us informed.

T.Wilson - MA

J.D.:

I'd think that it would be very interesting to compare side-by-side performance of PM2 and Locus units in solving long baselines (>>30km). One difference between the units may be how accurately each measures carrier phase. I say this knowing nothing about which chips each uses for that purpose.

Best regards,
Kent McMillan, RPLS Austin TX

Kent

I will have to do the ProMark2 on another night. Any night but a Saturday night. I was considering running a session tonight as the temps here are not to go below 50°. Had around 80° today. The ProMark2 has a little glitch with the "week roll over" thing. At the moment I'm just not up to dealing with it.

Thomas

You're right about the Lithium batteries, I'm sure. I just happened to have bought several "16 packs" of alkaline AAA's and figured I'd use them. I wasn't sure what 38° would do. Guess I found out.

JD

JD

Butting in on your thread...

When I posted the comment about the Promark 2 week rollover problem, Richard Phelan e-mailed me a workaround which works well. Essentially you need to download RINEX data from CORS (or another source) and convert to Ashtech format which creates an ephemeris file you can use instead of the Promark 2 logged file. It's a fiddle, but it's easy enough to do. Of course, partying on Sat nights is really the better option....

I second the battery reservations, the only way I have been able to get decent run times in our lovely warm (!) English climate is to adapt a Map330 external power supply by removing the locking screw. This works well and allows you to connect just about any 12v battery - we use 3.2Ah Yuasa's as a rule.

JC

Jon

Never consider yourself "butting in" on a thread, especially when you're adding to it. My data problem may not be due to the ProMark gps week roll over. Here's what's happening: I download the data from 5 CORS sites - DeQueen Arkansas (DQUA), Winfield, Louisana (WNFL), Arlington, Texas (ARL5), Houston, Texas (HOUS), and Beaumont, Texas (BEA5). The time span is date 02.027 from 0400 UTC to 0800 UTC (Saturday Jan. 26, 2002, 10: p.m. CST to Sunday January 27, 2002, 2:00 a.m. CST). The data for DQUA and WNFL comes in without a problem, all 4 hours as requested. The data for ARL5, HOUS and BEA5 refuses to download before 0600 UTC. In all three cases the data downloads 0600 to 0800. The only things in common are the three are all in Texas (which should make them correct), and they are all collecting 5 second epoch (I think). It's just another frustration to have to deal with.

Anyone have any suggestions about the CORS download and what caused this glitch?

J.D.

p.s. Jon, a lot of us here are anxious to see a manufacturer provision for the PM2 external battery. That would add tremendous value to the unit in my opinion.