Posts by pe1chl

    Probably now most of those RTL2832 devices are used for generic SDR purposes instead of the original purpose of DVB receiving with FM/DAB as side function.

    It is a bit sad that all the production volume now goes into these devices instead of a device optimized for SDR (some more bits in the A/D, no DVB decoder) that we probably could have got for the same price when produced in this volume...

    But anyway, it is incredible technology for the radio enthousiast.

    Exciting times we are in.. I wish I would be young again.. :P

    ... rings Peter in 1983

    "Peter, do you want a receiver that will receive from 25 to 1700 MHz, all-mode, will decode sat telemetry, and give a panorama overview of the entire transponder? It will be 30DM. and, a 3cm converter to go with it for 15DM"

    I think you would have considered that two zeroes were missing :-)

    In commercial GPSDOs a "digital PLL" is used where the VCXO is driven from the output of a D/A converter which is set by a processor which performs the PLL function and loop filtering.

    With this setup one can remember the last D/A value used across powercycles, so the lock is obtained a lot quicker than with a fully analog design that has to find the correct control voltage from scratch after powercycle.

    Even with that, those units often require 30-60 minutes to fully stabilize.

    The signals are back to their initial levels here. Anyone having trouble to receive or identify them should try again... these beacons are 30dB above the noise here when viewed in gqrx.

    (I am currently using an 80cm dish and an unmodified StarCom SR-3602 LNB)

    Good morning,

    I am using here an Octagon Oslo Optima LNB and a sdr usb stick. As reference frequency source for both devices i made a small circuit from parts lying around which delivers 25MHz for the lnb and 28.8MHz for the sdr stick disciplined via gps

    Unless you have special requirements it isn't really required to discipline the SDR stick. Those "1 ppm TCXO" sticks e.g. from RTL-SDR.COM are stable enough for typical amateur communications use. Also because the stick is indoors at room temperature, vs the LNB that is out in the weather.

    But of course it never hurts to tinker and experiment :-)

    That sure looks impressive! (both the device and the theoretical background)

    Not so easy to reproduce, I'm afraid.

    It depends if you want to optimize for gain or for "spillover" which will result in extra noise when receiving (not what we are doing).

    Sure, but this topic was about "which TX amplifier to use" and with AO40 a TX amplifier for 13cm was not required (at least in the operational state that it has been in).

    So probably it belongs in a topic about antennas.

    This weekend my StarCom SR-3604 arrived, the 4-output version that I ordered intending to convert it to use an external reference.

    Because the housing has 4 F connectors, it will be easy to use one for the reference input, and have 3 outputs for the Phase4A receiver and my normal satellite settopbox (2 tuners).

    Now I opened it, I have seen something interesting: there are actually 2 separate 2-output legs in this device, each with a PLL/mixer chip of type "1051" (I have not found anything about it yet) sharing a single unmarked crystal (probably 25MHz like the marked one in the SR-3602).

    I'm going to try to convert one leg to use the external reference and a single output, and keep the other leg on the crystal. So I can watch TV without the reference connected.

    (there are 4-output PLL/mixer chips as well but apparently they did not decide to use one of those)

    Same idea over here when I installed the dish in the summer... and it turned out to be a good idea to be able to check what's going on at 24°E before going to 26°E :)

    ..and who knows what will come after XMAS.. perhaps an Es'hail-3 ? :/;)

    I have had this setup for over 20 years. Long ago I could receive a lot of programmes and feeds even on 58w there was a beam towards europe, on 43w there were a lot of transatlantic feeds, also on 22w and 15w. There even has been an ATV transmission on 16e (PI6ALK) and of course random interesting things like Dr Dish, daily live relays of the late show wth David Letterman, etc.

    Most of it is gone, but I still use my dish a lot e.g. to receive BBC/ITV on 28.2e, German programmes at 19.2e etc. And now to receive Es'hail-2 :-)

    I receive it with an unmodified StarCom SR-3602 LNB and an SDRplay RSP1a.

    An RTL stick should show similar receive sensitivity.

    Is it an el-cheapo plastic one or the RTL-SDR.COM device in metal case?

    Those I am certain to work at that frequency, the plastic ones may get a little hot.

    To align the antenna connect a DVB-S receiver and tune for some FTA channel on Astra 3A. (23.5E)

    With all WiFi equipment (filters but also antennas) you always need to watch for the maximum rated power. These devices are normally used at 100mW..1W EIRP so very low transmit power. Of course there exist illegal power amplifiers but even those are usually not more than 4W.

    I don't have an amplifier yet, more or less I am waiting for an opportunity to buy either some surplus PA or a design from LZ5HP (sg lab) if it becomes available.

    But also I am not that eager to get on as the first one, and like to see what the realistic power requirement will be. For now I have 2W and an 88cm dish for which I still need to make a feed.


    The Spectrian amplifiers are cheap but they are extremely inefficient!

    Not bad when you need a heater, but as a 13cm amplifier... not so good.

    It means a big power supply is required. And maybe that much power is not needed at all, we need to see.

    At the moment (21:52 UTC) I have both the 10.706 beacon (with modulation) and the 11.205 beacon (but without PSK modulation) at the usual strength.

    This is at V polarisation but I think the beacons are RHCP so that should not matter.


    I don't have so many of those spurious lines, the empty spaces look like clean noise here, nothing inside the transponder band that I would mistake for a transmission.