dna@dsd.UUCP (03/08/84)
Posted: Tue Mar 6, 1984 1:54 PM PST Msg: IGIE-1733-3060 From: GRATCLIFF To: MSWEETING CC: AMSAT Subj: Uosat-2 Heard ? Martin, Last night I had a report from Darryl VK1DF who works at the Orroral Valley Tracking Station near Canberra. Two operators believe they have copied signals from UO-B on a number of occasions. 1. 4.3.84 approx 1235 UTC or time of closest approach no carrier but RFI detected and a questionable signal on 145.7317 Mhz ??? 2. 4.3.84 approx 2300 UTC a clean carrier on 145.825 Mhz for about the first half of pass, locked on to and measured carrier using 26M dish at -120dBM, then it went raspy and RFI sounding and could only be heard for a few seconds at a time. 3. 5.3.84 approx 1130 UTC raspy carrier but only for 3-4 seconds at a time and was -135dBM at point of closest approach. The times are somewhat approximate because the operators primary task at the time was their work in tracking Landsat D1. If you want to contact Darryl VK1DF his home phone number is (062)824380 at home for the next two days phone number at work is (062)357200 Graham VK5AGR Posted: Tue Mar 6, 1984 10:02 PM PST Msg: IGIE-1733-5260 From: PKARN To: amsat Subj: Orroral Valley observations A few calculations on the Australian observations: According to my handy-dandy Satellite Service Calculator (won as a door prize at the annual general meeting a couple of years ago), the 26M dish would have a gain of 29 dbi and a beamwidth of 6 degrees on 2 meters, assuming a feed efficiency of 50%. Working the reported signal strengths back to the spacecraft, the received level of -120 dbm corresponds to an EIRP at the spacecraft of -13 dbm over 1000 km. (That's 1/20 of a milliwatt). -135 dbw corresponds to -28 dbm over 1000 km, or just over a MICROwatt! The cosmic noise background behind the spacecraft varied over the course of the pass. At the 4 March 12:35 observation, the apparent position of the spacecraft was 6 hours 30 minutes RA, +23 deg declination; according to a 136 mhz radio sky map, the cosmos has approximately a 450 K effective noise temperature in this direction. This corresponds to a noise floor of -137.3 dbm, or a signal-to-noise ratio of 2 to 17 db in a 3 khz SSB bandwidth. The other passes apparently went in front of much noiser areas of the galaxy (1000-3000K) which would knock the S/N ratio down by 3-7 db. All this assumes that the galactic noise swamps the preamp noise, which is reasonable since a good GaAsFET has a noise temperature of 50-200 K. The message here is that the hearing conditions appear to be very highly variable, and while the chances for someone with a smaller antenna are obviously worse than with a 26M dish (!), there's still a chance that a well-equipped EME station (20 dbi gain) and good GaAsFET preamp should be able to hear the satellite on some passes. Conventional satellite stations are most likely not enough. Phil Posted: Wed Mar 7, 1984 11:42 AM PST Msg: PGIE-1734-1595 From: PKARN To: amsat CC: msweeting Subj: More elements I just called up Millstone Hill and asked if radar cross-sections were available for each of the pieces of 1984-021B. Unfortunately, they can only supply that information for deep space satellites, since they specialize in deep space tracking; for low earth orbits, they can only relay standard NORA element sets. In any event, I got a recent update on UO-11, and just to add to the fun, a set on the Delta 2nd stage. Satellite: oscar-11 Catalog number: 14781 Epoch time: 84067.06184980 Wed Mar 7 01:29:03.823 1984 UTC Element set: MH 3-7-84 Inclination: 98.2820 deg RA of node: 129.4940 deg Eccentricity: 0.0007918 Arg of perigee: 246.0900 deg Mean anomaly: 113.9370 deg Mean motion: 14.61892068 rev/day Decay rate: 0.00034636 rev/day^2 (this seems very high, don't trust it) Epoch rev: 78 Semi major axis: 7062.290 km Anom period: 98.502484 min Apogee: 707.238 km Perigee: 696.055 km Beacon: 145.8250 mhz Satellite: Landsat/UoSAT launcher Catalog number: 14782 Epoch time: 84067.08738720 Wed Mar 7 02:05:50.254 1984 UTC Element set: MH 3-7-84 Inclination: 100.0610 deg (this jumped up 2 deg over the weekend) RA of node: 129.6680 deg Eccentricity: 0.0144264 Arg of perigee: 294.6460 deg Mean anomaly: 63.9920 deg Mean motion: 14.92641153 rev/day Decay rate: 1.209e-05 rev/day^2 Epoch rev: 0 Semi major axis: 6964.974 km Anom period: 96.473288 min Apogee: 704.436 km Perigee: 503.477 km Posted: Wed Mar 7, 1984 9:44 PM PST Msg: KGIE-1734-5270 From: HPRICE To: amsat Subj: listening reports To: ALL FM: Harold Re: UOSAT-2 signal reports. We have received several more reports from people who hear various kinds of trash on 145.825. This is encouraging. What we need now is accurate aos/los times. We also need some indication of the amount of doppler you are seeing. It's ok if you didn't think you heard the whole pass, or if the signal fades so bad you can't be sure of when aos/los was. Just give us what ever you've got, and we'll add gains of salt as appropriate. We desperately need to make an informed choice from the several element sets available to us as to which one is uo-11. We are either too small, too close, or too silent to be sure. Give us what ever you've got. Even doppler (amount of frequency change) for a short period of the whole pass will help, since no change or too much of a change will tell us it isn't uo-11. Spotty aos/los times, if far enuff out of the expected range, can also tell us we're listening to the wrong thing. If you've already sent in a report, please go over your times and resubmit the report. If you haven't heard it yet, you may be missing one of the all time great T hunts. When we get the beacons turned on again later this week it will be too late, anyone with a wet noodle will be able to copy uo-11. If you're too embarrassed about the poor quality of your data, send it to just me or Phil. We won't tell. Harold.