ANTSDR: Low-cost SDR Alternatives for Ettus Research and Lime Microsystems | Hacker News Reader

ANTSDR: Low-cost SDR Alternatives for Ettus Research and Lime Microsystems

github.com

46 pointsteleforce12 comments

The AntSDR is a pretty solid piece of kit. It's compatible with the ADALM-PLUTO, so the available documentation is pretty great, and it's got both a compact and very solid construction (unlike a lot of the other offerings in the market).

The one thing to keep in mind (my experience is with the E200 though the E310 hardware architecture seems pretty similar from what I can see) is that the sampling rate is somewhat CPU bound by the onboard CPU. In spite of having a GigE interface, your sample rate will be limited to somewhere on the order of 110 MB/s which will give you a combined (Rx and Tx) sample rate of under 15 mega samples per second. I have heard of some people try to overclock these to boost the sample rate a bit. If that is all you need I could definitely recommend it though.

But the AD936x is directly connected to the programmable logic (FPGA) of the Zynq, not the PS (CPU), so you can either do the bulk of your processing (e.g. filtering, demodulation, possibly higher parts of a protocol stack) in the FPGA, or, if you absolutely have to, let the FPGA pipe out raw IQ sample packets onto the Ethernet, because IIRC the Ethernet controller itself can also be routed into the FPGA using MDIO, no?

I haven’t tried this yet (despite owning an AntSDR E200), but that’s what the schematics of the AntSDR and my prior experience with Zynq suggests.

You're right in that only the libiio firmware relies on the CPU to forward the samples out to the ethernet interface. The UHD firmware on the other hand does not seem to occupy the CPU to do this, however I have still had trouble getting transfer speeds to go much faster than they do with libiio (and I've had a lot of other problems with UHD personally). I'm not certain what could cause this limitation though.

In theory the hardware probably could do what you're describing if someone wanted to hack the FPGA internals themselves. I'd love to hear if you ever have any success getting things running better.

Given the way that the Ettus B2x0 SDRs shot up in price over the past couple of years, one would think that a UHD compatible SDR with similar capabilities would be flying off the shelves yet I don't see much in the way of reviews for these. Anyone who has one want to comment on how decent these things are?

A $30 RTLSDR actually does a reasonable job of receiving. I measured one at 0.1 uV sensitivity, which is surprising given the fact that the samples coming out of it are 8 bits of I/Q data. If you're trying to receive low bandwidth signals, such as AM/FM radio, SBB, Packet, etc... they're actually fit for purpose.

The FPGA based transceivers are out of my price range at the moment. If I were to dive into that field, I'd be using something with at least 8 channels, to do passive radar, and things of that manner.

A price of +300 USD just for the board itself isn't cheap.

The HackRF with PortaPack (battery, touch display, case and antennas) is selling for 130 USD with shipping included. That would still fit my definition of cheap around here in Europe.

I know someone will say "that is cheap for specialized radio" but you know what? That is just a bad argument, RTL-SDR can cost 5 USD per unit so you really don't need to pay that much for technology nowadays like in the 90s.

$5 is not even the price of the tuner (R860) at the MOQ of 4900 pieces. Where are you finding new RTL-SDR dongles for $5?

who still uses SDRs?

Don't confuse Software Defined Radio (SDR) with RTL-SDR, which refers to SDR with repurposed Realtek DVB-T sticks.

The realtek chip might drift into obscurity one day but SDR in general is certainly here to stay.

They're great for all sort of exploratory and prototyping work on the cheap. There's a pretty active community as well developing all sorts of software tools to give you a leg up.

why would u not ?

Most people listening FM on many cheap radios or on their phones are actually using SDR chips under the hood.

https://www.nxp.com/docs/en/data-sheet/TEF665X_SDS.pdf

https://eu.mouser.com/new/skyworks-solutions/skyworks-si468x...

...and others.

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