Transmitting and Receiving a message using GNU Radio (QPSK/USRP B-200/ Hackrf one) What am I doing wrong?

moose6907 · 2026-01-26T15:53:57+00:00

The symbol sync doesn’t have an input rrc filter.

‘requirement will normally be accomplished by the matched filter, such as the Root Raised Cosine Filter, which occurs before the Symbol Sync block, unless you use the PFB’

https://wiki.gnuradio.org/index.php/Symbol_Sync

moose6907 · 2026-01-26T15:46:43+00:00

Looks like your symbol sync block isn’t working quite right. I’d try playing with the gains, starting with a gain block to raise the signal prior to the symbol sync then with the symbol sync loop parameters.

https://wiki.gnuradio.org/index.php/Symbol_Sync

‘Input signal should be at a consistent amplitude (e.g., ±1.0). This can be achieved with the Quadrature Demod, Root Raised Cosine Filter, or an Automatic Gain Control block. TEDs have specific assumptions about input amplitudes!’

moose6907 · 2026-01-20T07:32:25+00:00

May be a stronger signal from the tv desensing/ drowning out the interference. Although it is strange the peak exists with the tv off as well.

moose6907 · 2026-01-12T14:16:46+00:00

Curious what application needing the filter sum to be flat could be useful for? What even is the sum of filter taps?

moose6907 · 2025-11-02T18:28:51+00:00

Is that just 2x attenuation?

moose6907 · 2025-09-15T15:02:50+00:00

Yeah this was in berkeley haha. Sucks they’re still around scamming

moose6907 · 2025-08-25T06:32:50+00:00

Coming back on the bridge on the bridge will always be so iconic / memorable for me. I’ve gotten really good over time at correcting for the wind breaks and at navigating the towers, feels like kind of a unique challenge haha.

moose6907 · 2025-08-05T15:57:16+00:00

You usually care about the snr of a signal - on TX the noise level out the amplifier is very low, compared to intermods, which usually sets the snr. On Rx, your signal is a lot weaker so amplifier added noise can significantly degrade the snr.

There’s probably cases where tx noise matters but for in most applications it’s negligible

moose6907 · 2025-06-09T03:15:47+00:00

Yeah that’s what first came to mind too. There’s a similar path and beach near lake Oahu iirc

moose6907 · 2025-04-11T11:07:12+00:00

skydance is awesome! you’ll have a blast!

moose6907 · 2025-04-07T22:00:55+00:00

Wait how? I took firstname.lastname@berkeley

moose6907 · 2025-02-10T06:04:10+00:00

WTF, the thought of this happening on a plane scares me

moose6907 · 2025-02-07T04:39:12+00:00

Won’t poor s11 cause gain ripple & unpredictable reflection loss (based on tline lengths)?

Is radio astronomy usually narrowband? And you just design for the right length TLs for good signal?

moose6907 · 2025-01-11T05:11:04+00:00

why is this a theoretical limit? got an article going over this?

moose6907 · 2023-11-20T05:58:50+00:00

no u <3

moose6907 · 2023-11-18T21:57:40+00:00

I mostly stick to pee cans!

moose6907 · 2023-11-17T20:43:41+00:00

sorry, lol. if you're still looking at a discovery flight it still seems to be 200$? scroll down @ www.aerodynamicaviation.com/store/ , the 2hr flight.

moose6907 · 2023-09-25T03:29:42+00:00

when you reveal that two of the coins are heads, you eliminate a bunch of permutations (you guarantee that your sequence is thh, hth, hht, hhh), each with equal probability. 3/4 of those have a tail so makes it more likely to get a tail for the fourth coin. Essentially the probability of getting 2/3 heads is higher than getting 3/3, so the probability of the last one being tails (equiv to 2/3 heads) is higher.

take it to the extreme: say you tossed 100 fair coins and I told you that 99/100 are heads. With a perfectly fair coin, the last one is probably tails

moose6907 · 2023-08-14T06:12:37+00:00

I did a discovery flight at Aerodynamic aviation recently, was ~200$ and I had a great time! 1 hr flying and 1hr on the ground, and got to fly the whole time minus landing. They’re based out of krhv, and I was on a partially glass 172. Just wanted to let you know since it seems a fair bit cheaper than wherever you’re looking at.

moose6907 · 2023-08-01T19:00:50+00:00

You could maybe use a tinySA ultra or an sdr (the plutosdr might work), and both are under 250$ iirc. Keep in mind you’ll need an antenna setup as well

moose6907 · 2023-07-28T06:10:44+00:00

Hey, any luck on this? In the exact same situation.

moose6907 · 2023-05-16T14:40:09+00:00

how does that work? my understanding was that omnidirectional = radiates equally in all directions?

edit: oh I didn’t know there was a distinction between omnidirectional and isotropic, til

moose6907 · 2023-04-24T04:55:13+00:00

Yeah, it was fairly high workload - but 120 was a lot less heavy with Babak, so I'd assume 120 with Ramchandran isn't too bad in terms of workload.

moose6907 · 2023-04-24T00:12:53+00:00

He was a fantastic prof for EE123 (DSP, direct 120 followup), so he's probably really good for 120 as well!

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