Re: [Discuss-gnuradio] Evaluating PlutoSDR with DVB-T example dvbt_rx_8k

[Marcus D. Leech]

On 11/13/2018 06:06 PM, Ron Economos wrote:

I believe the sample rate of 8 MHz DVB-T is beyond the capability of the Pluto. The required sample rate is 9.14 Msps, which exceeds the throughput of USB 2.0.

Ron

Actually USB2.0 should be just fine up to about 10Msps with 16-bit I 16-bit Q.   But the PlutoSDR, as shipped, cannot keep up with that.

There are some "tricks" including turning on the 2nd CPU core, and also running a completely-different system image that bypasses all
  the IIO stuff, but gives you better RX-only performance.

On 11/13/18 10:33, Rudolf Wigblurr wrote:

Hi!

I'm validating if a new ADALM-PLOTO is fully working or not.
Attached is a modified version of the dvbt_rx_8k example (test_dvbt_rx_8k_copy.grc)

 

1. Source from adv64.cfile

 

A correct result I think.
Both Constellation are steady even with noise added.
See "test_dvbt_rx_8k_copy.adv64.png"

 

2. Source from PlutoSDR

 

Incorrect.
First Constellation shows signs of pilot but it is not stable at all.
Second Constellation show just a dot.
See "test_dvbt_rx_8k_copy.pluto.png" and "animated.gif"

 

Input is the local terrestrial TV from my antenna on the roof.

According to the Terrestrial broadcast company there are 4-modes for DVB-T

 

Bandwidth: 8MHz
FFT size: 8k
Modulation: 64QAM
Guard Interval:  1/4, 1/8, 1/32, 1/4
Code Rate:  3/4, 2/3, 2/3, 2/3
Hierarchical: non

 

Played around with a lot figures without getting anything better than attached gif
There are no signs of overruns.

CPU load is 100% on one core rest 5-10% on a i7-4770K @ 3.5

 

OS Fedora 29
Kernel 4.18.17-300.fc29.x86_64
GNU Radio Companion 3.7.13.4
PLUTO build from latest git

 

Is Pluto skipping or ....?

 

/Rudolf

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