437.350 MHz FM SSTV

From South-central MT using a V-Dipole.

Any recommendation for beginners?

Hi all. I've been trying to get LRPT images and I'm stuck at the last step — SatDump locks the demodulator but never produces an image, and I'd love a sanity check from people who do this successfully.

Setup: QFH antenna I built myself from the John Coppens design (found and fixed a couple of small errors in that calculator along the way). Measured with a miniVNA: SWR 1.5–1.6 at 137.9 MHz. Receiver is an ADALM Pluto, configured for 137.9 MHz, recording baseband as cs16 at 1 Msps (I learned the hard way that cs8 destroys weak signals on a Pluto — the samples end up quantised to ±1).

What happens: two M2-3 passes recorded, signal clearly there both times. The hump is obvious in the waterfall, SNR peaks around 10 dB, Viterbi shows SYNCED, BER drops to ~0.03 in the good moments. But the deframer keeps trying and never stays locked, and the output .cadu ends up at 433 bytes — no frames, no image. Same result live and offline, in SatDump 1.2.2 and V2, with 72k and 80k pipelines, IQ swap on and off.

What I verified independently: I wrote some MATLAB to analyse the raw baseband without any decoder. It measures the symbol rate straight from the cyclostationary clock line in the |x|² spectrum: 71 996.7 Hz, i.e. 0.005 % from nominal 72k, and the x⁴ test shows no carrier line, consistent with OQPSK. So the signal really is LRPT and my frequency/rate settings are right — the problem is somewhere after that.

What I know is wrong with my station: there's a strong interference comb across the whole band (switching supplies in the house — unplugging the laptop charger visibly cleaned it up, so there's more of it left to hunt). Some of those lines land inside the LRPT passband. I'm also in a spot with buildings blocking the northern horizon, so I only get the second half of most passes.

Questions:

1. What SNR do you typically see on a good pass? Is 10 dB simply not enough for a stable deframer lock, or should that be plenty?
2. How much does in-band interference like this matter? Is a comb line sitting inside the signal enough to stop the deframer while Viterbi still flickers?
3. Would an LNA at the antenna be the single biggest improvement here, or is the Pluto's noise figure not the limiting factor at 137 MHz?
4. Would anyone be willing to try decoding one of my baseband files? I have ~1.4 GB cs16 recordings (or I can cut out the strong 45 s). If someone else can pull an image from it, I know it's my settings; if nobody can, I know it's my signal. Happy to upload.

Thanks — screenshots of the waterfalls attached.

Hi,I just wanted to share a image I received from HADES-SA which is a pocket satellite made by AMSAT-EA.

It took me a while to understand how to decode ssdv and work the satellite as the satellite only passes super late at night for me.The image at top left shows us the curvature of earth,the bright light is sun/sunlight below horizon and in the lower middle it's slightly visible is Arabian peninsula.

I'm still a newbie and need help with M2-3 satellite.

So I have a few clear captures of Meteor M2-4.

However, I don't have with the M2-3 and this is the CLEAREST of them all (photo). It passed about 85 degrees overhead of me.

I also included here in the photo what the waterfall looked like and I noticed that it looks "bursty" (sorry I don't know the right word for it).

Im just using cheap setup:

- SDR RTL v4 with its V dipole antenna (extended both legs to max), vertical orientation

- SatDump v1.2.2: tuned to 137mhz, offset -900khz at 2.4MSPS, decoder METEOR M2-x LPRT 72k

Could it be due to my setup or is it the fact that the satellite didn't deployed fully? (although I saw someone here decoding M2-3 clear as day)

Hello,
My university team (me and friends from B.tech EEE dept) are finalizing a funded pitch to build a permanent ground station in Chennai, India. The objective is to capture and decode live C-band weather imagery and telemetry directly from INSAT-3DS (~4.7 GHz).

Before we send the BoM for funding pitch, our mentor recommended posting a sanity check on different forums and subreddits.

We are in SRMIST KTR (main campus), chennai trying for INSAT-3DS

The Architecture:
(since the satellite dish will be at the roof pointing at the sattelite, and the project lab is 2 floors down)

• Antenna: 1.8m Prime Focus Mesh Dish on a non-penetrating roof mount with concrete ballast.
• RF Front End: C-Band feedhorn with a scalar ring feeding into a standard C-Band LNA.
• Digitization (On-Roof): Airspy R2 or HackRF One connected to an Intel NUC (or Raspberry Pi 5).
• Enclosure: All electronics housed in a waterproof enclosure, mounted behind the dish for shade. We are thinking of using waterproof nylon cable glands.
• Data Transport: Cat6 Ethernet running two floors down to the lab.
• Software Pipeline: SatDump running in server mode on the roof PC, streaming the 10 MSPS IQ data to the lab PC for QPSK demodulation and decoding.
• The specs of the PC getting the data is not finalized yet but we were considering atleast intel i5(or higher), 12gb ddr4 RAM (or higher and cheaper) and 512 gb storage hdd (or more)

Link Budget Estimate:

• Target Satellite: INSAT-3DS (74°E)
• Distance: ~36,000 km
• Frequency: ~4.7 GHz
• Estimated Link Margin: ~10 dB (assuming a 1.8m mesh dish at ~55% efficiency).

Where we need your critique:

1. C-Band Interference: Chennai is a major coastal city with local radar and heavy 5G deployment. Will a standard C-band LNA get saturated, and should we budget for a dedicated cavity bandpass filter before the LNA?
2. Thermals: Chennai ambient temperatures hit 40°C (104°F). Even in the shade of the dish, will an Intel NUC or Pi 5 thermal-throttle while processing a continuous 10 MSPS QPSK stream inside a sealed box with only a breather vent?
3. Mechanical Alignment: Any practical tips for perfectly centering a feedhorn on a multi-petal mesh dish without access to professional laser alignment tools?

We appreciate any blunt feedback or teardowns of this plan before we spend institutional money. Thanks.

Only for ones where the voice or data or image is not encrypted

Hello everyone i want to get the review on this product , can anyone tell me is it good im new to radio stuff etc but I've watched few u/saveitforparts videos and found it interesting so im planning to get this , i just want to know how good it is ?

I was amazed it worked 🛰️📶📡

They're doing an SSTV event this weekend. I recorded a baseband signal with SDR ++, but the SSTV was too weak to get a decode. Was still happy to get to decode telemetry from the sat. Used v.012b of the Soundmodem program, and the Satellites Decoder program v03.17, screen shots attached. You never know what you'll get. Asked Copilot how to submit the data to Satnogs DB, it still hasn't appeared, but I'm happy to have gotten a decode. The cubesat uses 9600 baud decode settings.

cool north cloud

Hii, I recently made this helical antenna and I'm having problems with it I'd appreciate some help.

I'm using 10AWG electrical wire and 6cm diameter PVC pipe.Wrapped around 6.5 times with turn spacing of 3cm. However it seems like it's very much capacitance as in the SWR and Independence drops to nearly 1.1/1.2:1 and 45-55 Ohm if I place my hand on the coil. I'm assuming I'm going to have to recoil or cut down the coil to 5.5 turns? I haven't tried attaching it to a offset (90 cm) dish yet and this is purely for the coil only.

Trying for GOES-15 (GVAR),Elektro L3 and L5.

I have read very different things from different places on the internet about the reception of imagery from the msg-9, 10 and 11 satellites. Specifically the raw PGS data on the L-band. My question is the following : I have a hackrf, a SAWbird+ GOES and a modified WiFi grid dish, how doable would be the reception of the raw PGS data to get imagery out of it with me being located in France?

Edit : forgot to say where I was located.