Many of you have no idea what goes on when AO51 is in the S band downlink mode. Until this past week, I was in the dark as well. Who operates S band and what is it like compared to the more popular V/U mode? What kind of equipment does it take to get on S band. If you don't have S Band equipment, should you invest in some? Are you going to work anybody new or perhaps a new grid? After a week of making q's and listening to 29 passes of S band, there is some data and observations to share.
A lot of people are using the K5GNA setup. My setup was quite different. The antenna used was a Hyperlink Technologies (now L-Com in Florida) 18dbi Wifi Panel Antenna. It is well made and comes with stainless mounting hardware including a 2-1/2" U-bolt that will fit most any mast. It's about 2" thick and 14"x9" rectangular. Price is $50, not bad for a well made weatherproof outdoor antenna. The Down East Microwave preamp kit and outdoor housing for it is about $85. The outdoor box is as expensive as the preamp kit itself. It was mounted on the antenna with a 7' 9913 pigtail. The 45' of coax into the shack is 3/8" Andrew Heliax. In the shack is a Drake 2880 down converter with a new crystal from G0MRF to get the output on 145 MHz. Both the preamp and the downconverter are powered through the coax so you need two power inserters. I used a second radio for the IF so that there was no chance of transmitting into the downconverter. Doppler is about =/- 55 KHz from horizon to horizon. You can see what it looks like on the tower on my qrz.com page. Click the image to enlarge.
At first I was disappointed because I am used to hearing 435.300 down to the horizon in most directions. It didn't happen with S-band. But after listening to other stations, it was apparent that my setup was hearing better than most. There has been discussion about the slow roll of AO51 and that is certainly apparent, however, I could not hear much below 6 degrees, ever. Maybe a bigger antenna would help out, but those that were active didn't seem to have any better receive capabilities so it makes you wonder.
Now for the activity data. Below is each pass that I operated or listened to and the stations I worked (with an asterisk) or ones that I just heard (no asterisk).
8/16/2009 2245Z (first S-Band mode pass) KC9ELU* KJ4MC KD8CAO*
8/17/2009 0036Z KC9ELU* N6PAA W7LRD
8/17/2009 1053Z KC9ELU*
8/17/2009 1234Z VE2DWE* KC9ELU* KD8CAO* KB2M* W8KHP N5ZNL*
8/17/2009 2359Z W8KHP* N5ZNL* VE2DWE* W7JPI* K5WH* W7LRD* K9QHO*
8/18/2009 1151Z WB8OTH* W7JPI* N5ZNL* W8KHP*
8/18/2009 1331Z K9QHO* W7JPI*
8/18/2009 2128Z WB8OTH* KC9ELU* W8KHP
8/18/2009 2305Z W7JPI* KC9ELU N0JY* W8KHP* N5ZNL K9QHO KD6IRE? XE2BHL
8/19/2009 1116Z KC9ELU
8/19/2009 1252Z WB8OTH* XE2BHL* KC9ELU*
8/19/2009 2230Z W8KHP* VE2DWE*
8/20/2009 0006Z N5ZNL/P* N5UXT* N0JY* VE2DWE* W8KHP* WB8OTH W7LRD*
8/20/2009 1213Z KC9ELU* KB2M* W8KHP* N5UXT* N5ZNL
8/20/2009 1353Z AI7W* W7JPI* KC9ELU WB6QVU?
8/20/2009 2153Z NO STATIONS HEARD
8/20/2009 2326Z W7JPI W8KHP K9QHO W7LRD WHISTLER
8/21/2009 0111Z 2 DEGREE PASS, NOTHING HEARD
8/21/2009 1145Z N5ZNL* KB2M*
8/21/2009 1314Z KC9ELU* N5UXT* W7JPI*
8/21/2009 2246Z KG4ZLB* WB8OTH* N0JY* W8KHP* AK5V*
8/22/2009 0029Z AK5V* KB2M N0JY* W7LRD*
8/22/2009 1053Z KC9ELU* KB2M*
8/22/2009 1234Z KC9ELU* W7JPI* K8KHP*
8/22/2009 2207Z KC9ELU*
8/22/2009 2347Z WA5KBH* WD9EWK* N5ZNL* XE2BHL* KC9ELU*
8/23/2009 1156Z W2NBJ* KC9ELU* WA4SCA*
8/23/2009 1332Z KC9ELU* W7JPI* N5UXT* XE2BHL
8/23/2009 2127Z KC9ELU* N1RCN*
Mike, KC9ELU was on vacation this past week and was the most active station on S-Band. It was interesting to compare our reception and have airtime to discuss it.
The only new guys I'm aware of were myself and N1RCN who got things working on the very last S-Band pass. Drew, where were you?
Some have been asking for more S Band, but if you take a look at the activity, it pales in comparison to what we have in the V/U mode. The last AO51 V/U pass tonight (8/25/2009 0007Z max elevation 17 degrees to the west for me) had at least 23 stations on it. More were trying. It's a Monday night! I never heard more than 8 stations on any S-Band pass, and there were plenty with just one, two or three.
If you have AO40 equipment laying around, you might be a good candidate for S band. But unless you are prepared for a very high dollar investment/qso, you probably won't be buying S-Band equipment to work the few stations that get on that mode. If you want to do L/S, there will most likely be even less activity since making noise on 1.2GHz is even more expensive. (When L/S comes on, I'll have another report.) My antenna system could be improved but there's not much point in spending more effort and putting more windload on the az/el rotor to hear down to the horizon.
We need to balance the interests of everyone and that is understood. We need some V/S or L/S from time to time. I'm not sure, however, that an entire week should be devoted to it considering the usage. Maybe a few days at a time would make more sense. You work on your equipment and get ready for the three day period. If your setup doesn't work, you figure out why and get on the next time. Shorter sessions would focus the activity rather than spread it out over a week's time.
We should do things that will interest new people in working satellites. V/U is the entry level for newcomers and we should make that available as much as possible. There are other FM birds, but nothing compares to what AO-51 does to attract new hams to satellite technology. It's signal level, available time/pass and morning/evening pass schedule over the US are ideal.
There is a lot of debate over what we should be doing for the future. But it is as important to debate how we should use the resources we have available to us right now. My hope is that this post will inspire some constructive comments and discussion on this subject.
John K8YSE
Drew, where were you?
Digital side collecting WOD files, and much of the time at work. Summer is the time for field work in geology and geophysics, and that's what pays the bills. Last week I was in Tallahassee most of the week, and very busy. Sat time was done remotely over the web, checking in to collect files that WISP downloaded automatically. This weekend and week I'm steering the ship (mediocrely) while Gould is away.
If you have AO40 equipment laying around, you might be a good candidate for S band. But unless you are prepared for a very high dollar investment/qso, you probably won't be buying S-Band equipment to work the few stations that get on that mode.
S does not have to be expensive. A few years ago there were AIDC downconverters on Ebay for less than $50, and building a helix is practically free. Many folks like S for the challenge of building and modifying the gear for cheap. Heck, we even have some folks who use surplus MMDS downconverters that were found on Ebay for $6 each. A 2m HT, a surplus downconverter, a scrap of wire, and a scanner, and you are in business.
We need to balance the interests of everyone and that is understood. We need some V/S or L/S from time to time. I'm not sure, however, that an entire week should be devoted to it considering the usage. Maybe a few days at a time would make more sense. You work on your equipment and get ready for the three day period. If your setup doesn't work, you figure out why and get on the next time. Shorter sessions would focus the activity rather than spread it out over a week's time.
We've tried both ways. Having modes run in one week increments is easy to schedule, easy for the command team to implement (we are usually home on Sunday evenings), and easy for folks to remember when the mode change is. We've had 5 years to tweak this equation, and this is what works best in the current situation. You have one point of view that you have expressed to me before, and there are a myriad of other, often conflicting, viewpoints. Comprimise is not an easy task. Single mode satellites are so much easier.
We should do things that will interest new people in working satellites. V/U is the entry level for newcomers and we should make that available as much as possible.
It's available every day with or without AO-51 on 5 or 6 other satellites. However, without AO-51 there is no S and no L at all. Once you have mastered V/U, where to next if not L or S on 51? We've personally discussed this several times in the past. If SumbandilaSat is as successful as I think it will be with it's 4 or 5? watt downlink, you may find AO-51 in S more often than now. If Kiwisat works well on L up, or someone ever reloads GO-32 with the L BBS uplink, we may cut back on L time. Another issue is that once the next two full illumination periods are over, we may have a hard time running the S transmitter at all, due to power requirements and the deteriorating batteries. AO-51 by mid 2011 will likely not be able to support the S transmitter at all through eclipse, and will then revert to just V/U or L/U ops, and with only one transmitter at a time. Hopefully we'll have another S downlink by then, like Delfi Next, or maybe an AMSAT-Fox.
There are other FM birds, but nothing compares to what AO-51 does to attract new hams to satellite technology. It's signal level, available time/pass and morning/evening pass schedule over the US are ideal.
Maybe for you. Do you speak for everyone? I happen to think the AO-51 pass times are really poor now. I'm getting ready for work in the morning, or driving there, and eating dinner or driving home for the evening passes. AO-27 is about the same power level as AO-51 usually is, and is actually stronger for those using Arrows who match polarization with the downlink, since 27 has a linear downlink and 51 circular. SO-50 offers pass times that change from week to week, offering the newbie a chance to get on late night or early morning and not be trampled by grid chasers or the "breakfast club" saying hi to each other for the third time that day. 51 is hard to use for club meeting demos since the passes are over by the time the meeting even starts. I've switched to using AO-7, FO-29 or VO-52 for evening demos. Same for hamfests since the doors aren't open by the last morning pass, and everyone is home sorting their loot by the afternoon passes.
There is a lot of debate over what we should be doing for the future. But it is as important to debate how we should use the resources we have available to us right now. My hope is that this post will inspire some constructive comments and discussion on this subject.
I welcome the input, and the modes committee and I read and consider everything we get, and most of what we see on the -bb that is relevant. However, I've noticed there has been a lot of politicking and jockeying lately about scheduling, and I wish it would stop. Send the committee your own personal wishes, and rest assured that we are doing our best to meet everyone's requests, and represent all interests. It's not an easy job, and the less politics we have to deal with, the easier it is to do.
Glad you enjoyed V/S, and take this in the friendly spirit in which it was offered.
73, Drew KO4MA AMSAT VP Operations
John,
Interesting report. It was good to work you during the last V/S period. I have been on that mode for years, as well as L/S, but you quickly get your WAS, Worked All Stations. Glad to see that the number is expanding.
I came across a G3RUH 60 cm dish with a circularly polarized patch antenna. It was originally used for AO-40, and so it is superb on AO-51. I have an SSB LNA mounted directly at the feed, and use some old RF-213 to feed the signal about 65' to the converter in the shack. There is plenty of gain, and using hard line is unneeded. In fact, I have a variable attenuator to balance the gain properly. Works fine, horizon to horizon. In fact, I see more distinct limitations when using the mode-L uplink.
Alan WA4SCA
participants (3)
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Alan P. Biddle -
Andrew Glasbrenner -
John Papay