BW(Sample Rate) Issue

[Rohith Rajan]

I am asking a doubt regarding receiver using an  Adalm Pluto SDR
In the receiver section we are using *Polyphase Clock Sync*, *Linear
Equalizer* and *Costas Loop.*
My doubt is that is the configuration parameters of these blocks are
dependent on the BW of the signal(Sample Rate)

Keeping the parameters as Normal  (*In Polyphase Clock Sync block*- No of
filters(nfilts) as 32, Loop Bw .0628, RRC filter as

*firdes.root_raised_cosine(nfilts, nfilts, 1.0/float(sps), 0.35,
11*sps*nfilts), sps as 4*

;* In Linear Equalize*r No of Taps as 15 ;In CostasLoop Loop BW as .0628)
when I set the BW(sample Rate around)1MHz I can receive the datas.

But when I set the BW(Sample Rate) as 125KHz I cannot receive the datas.

Anyone plese tell me what modification I have to make ?

Re: BW(Sample Rate) Issue

[Cinaed Simson]

Hi Rohith - Ihe minim sampling rate  for the Pluto is in the ball park 
of 500 KHz.


See

https://ez.analog.com/adieducation/university-program/f/q-a/557730/pluto-sdr-sampling-rate

-- Cinaed


On 11/30/22 05:54, Rohith Rajan wrote:


I am asking a doubt regarding receiver using an  Adalm Pluto SDR
In the receiver section we are using *Polyphase Clock Sync*, *Linear 
Equalizer* and *Costas Loop.*
My doubt is that is the configuration parameters of these blocks are 
dependent on the BW of the signal(Sample Rate)


Keeping the parameters as Normal  (*In Polyphase Clock Sync block*- No 
of filters(nfilts) as 32, Loop Bw .0628, RRC filter as


/firdes.root_raised_cosine(nfilts, nfilts, 1.0/float(sps), 0.35, 
11*sps*nfilts), sps as 4/


;* In Linear Equalize*r No of Taps as 15 ;In CostasLoop Loop BW as 
.0628) when I set the BW(sample Rate around)1MHz I can receive the datas.


But when I set the BW(Sample Rate) as 125KHz I cannot receive the datas.

Anyone plese tell me what modification I have to make ?

Re: BW(Sample Rate) Issue

[Glen Langston]

Hello Cinaed,

I’ve not experienced this problem with Gnuradio you describe, but
in another context, spacecraft communication, we had a simple test setup
that transmitted a fixed pattern of alternating ones and zeros.

However the way error coding was done the lock was always poor.   

For testing purposes you might have much better luck by sending a “sudo-random”
noise sequence that you define and write into the transmit code.Then
test that this code arrives correctly on the receive side.   

We found the lock was very reliable, for the noise-like sequence.

Hope this helps, but just a guess

Glen


> On Nov 30, 2022, at 3:54 PM, Cinaed Simson  wrote:
> 
> Hi Rohith - Ihe minim sampling rate  for the Pluto is in the ball park of 500 
> KHz. 
> 
> See
> 
>   
> https://ez.analog.com/adieducation/university-program/f/q-a/557730/pluto-sdr-sampling-rate
> 
> -- Cinaed
> 
> 
> On 11/30/22 05:54, Rohith Rajan wrote:
>> I am asking a doubt regarding receiver using an  Adalm Pluto SDR
>> In the receiver section we are using Polyphase Clock Sync, Linear Equalizer 
>> and Costas Loop.
>> My doubt is that is the configuration parameters of these blocks are 
>> dependent on the BW of the signal(Sample Rate)
>> 
>> Keeping the parameters as Normal  (In Polyphase Clock Sync block- No of 
>> filters(nfilts) as 32, Loop Bw .0628, RRC filter as
>> 
>> firdes.root_raised_cosine(nfilts, nfilts, 1.0/float(sps), 0.35, 
>> 11*sps*nfilts), sps as 4
>> 
>> ; In Linear Equalizer No of Taps as 15 ;In CostasLoop Loop BW as .0628) when 
>> I set the BW(sample Rate around)1MHz I can receive the datas.
>> 
>> But when I set the BW(Sample Rate) as 125KHz I cannot receive the datas.
>> 
>> Anyone plese tell me what modification I have to make ?
>> 
> 

Help Needed for Differentiation Implementaion

[Shuvodip Majumdar]

Hello all,

I am currently at the example "symbol_differential_filter.grc" in the GNU
Radio tutorial. It's in the chapter "QPSK Mod and Demod". My question is
how taps [-1, 0, 1] is implementing the differentiation in "Decimating FIR
Filter" block.


For first difference, the equation should be y[n] = x[n] - x[n-1]. In that
case the taps should be [1, -1]. Here is my confusion. Why taps [-1, 0, 1]
have been used and which difference it is implementing?

Regards,
Shuvodip