Day 3 Update:
The small amount of snow that did fall yesterday eventually burned off this morning; if anything the field got a little muddy/mucky but nothing too serious. Ray and I still stayed indoors with the intention of performing the same tests that we had done on the West radar to the East. However, Ray noticed when we got into the building that the restricted frequency file seemed to not be working properly. We've been working with Jef to correct this issue. We also changed around a few other things in the software including an *update* to the 'hardware.dat' files that the radar was using. We downloaded the file from the VT website and added in the parameters that we found the radar to be using before we made changes. We suspect there may be a sign issue in the velocity measurements...
After making these software adjustments, we turned back to making RF measurements on the RX path of the west radar. Surprisingly we found that NONE of the transmitters on the west radar needed any repairs at all. As with the east radar, we then looked at the RX'ed signal levels through the phasing matrix and again did not find anything damaged/broken at this stage. Finally, we went through the divider/combiner and looked at the received signal strength; again no surprises.
In a final part to looking at the receiver path, we looked at the sky RF/IF coming through the receiver front end for both radars and found that the signal/noise levels were comparable. All and all, just about everything is working as well as we can get it during this trip on the receive path.
I did some quick measurements of the ground coax and the antennas on the west radar and seem to have some knowledge on where things are failing. With better (and slightly warmer) weather predicted for tomorrow we may be able to venture outside in order to try some quick/easy tests on these components in order to better identify the problem.
I also got the peak Wattmeter working again and took some ballpark measurements on the peak power coming out of some of the transmitters. We seem to now be tending around 500 W_peak on the output. That's about all for now! (One more day left)
Day 2 Update:
Well we woke up to at most 2 inches of snow with reports that we're still expected to get more. In the end...it all was for nothing. We got a few inches at the radar site and it seemed like even less fell in town. It did make some interesting times navigating the dirt roads with the Mustang. Also, NO HIGH WINDS Mike! (You wouldn't have wanted a high lift in the snow anyways)
We stayed indoors out of the weather though by continuing repairs on the East transmitter RX paths. We found high power T/R switches, Mini-Circuits amps, and even one controller card that were damaged/not functioning. The high power T/R switches and controller cards were simple to fix since we have a good supply of parts...the Mini-Circuits amps are not so easy to repair or replace as we don't have spares...
We ended up repairing as much as we could, using some spares, and swapping some out in order to run as many transmitters as we could. The East now is running on 14 transmitters, having 2 TXs out because the antennas or ground coax is bad. With the TXs as repaired as much as possible, we then added the phasing cards into the RX path measurements on the East radar. We didn't find any phasing cards that were bad/damaged! (So no repairs).
We've also gotten instructions on how to change the RF drive levels being applied to the transmitters by software. With instructions from Jef we'll be able to tweak the output power of the transmitters as we see thats needed. We also applied changes in the software to have the normalscan and themisscan control programs use 100 range gates.
Day 1 Update:
We started the cold and snowy/rainy/wet day by trying to do some electrical length measurements on the ground coax again. We were able to reproduce Todd Parris' measurement and able to use another technique to get fairly consistent measurements. However, the two techniques seem to disagree in the exact electrical length of the ground coax cables. We've taken down measurements and will debate this further.
ON TO NOISE MEASUREMENTS! We then took to measuring the signal & noise levels at the building end of the RF ground coax. From these measurements, we've identified where we have bad RF loads either because of the antenna or from the RF ground coax. In the case of #1 on the West, we're fairly certain its because *someone* cut off the connector on the antenna side of the ground coax...we'll fix that one of these days.
From there, we continued down the RX path by looking out toward the antenna through the transmitters on the East array. Here we found some significant problems with signals being passed through the transmitters. We were able to fix one by repairing the high power T/R switch. However, we also found a Mini-Circuits amp on the RX path that was burned out and not amplifying as it should have.
We're still staring down 5-10 inches of snow under a Winter Storm Warning here in Hays. We'll see how our Mustangs far in the snow...we may be parking at the outside of the fence and walking in.
__
Travel day__ was completed on March 6th and somehow Ray and myself ended up with matching fire engine red Mustangs...
It's good that the outdoor work was put off until another time as we're under a Winter Storm Warning here in Hays through Tuesday night. Brr!
Maintenance trip to Hays, Kansas March 6-11
By: ksterne on: Mon., Mar. 07, 2011 11:30 AM EST (7813 Reads)
|
Day 4 Update:
Today we started off my doing a few more software adjustments in the radar software. We also did some more measurements on the receive path, some of which were a repeat of the previous day's measurements. From these measurements we were satisfied by how the radar was preforming during receive. With the afternoon to finish up a few 'here and there' items, we boxed up the items we'll need to prepare for the West reflector build. It was most certainly interesting trying to get a spool of guy wire into the mustang. Thanks goes to Ray for taking one for the team and making a few car rides in the back of the car! However, all of the items are on the way to Blacksburg. We also did some diagnosis of the RF ground coax and antennas as a preparation for the next trip. We were actually able to bring several of the lines back on line and now have transmitters able to pass power. The best news of all of this was NONE of the RF ground coax cables were bad!!! (No digging up cables!) Now we are mostly limited on the two radars by not having enough transmitters that work on the RX path, although this will require some additional parts. Otherwise, it was a shorter day today as we accomplished everything we wanted to do. I packed up and got all of the things to cart back to the lab. Ray will have the morning tomorrow before he begins to head home. |
