RSP1A: wobbling spurs around 2.335MHz * n

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DK7OB
Posts: 65
Joined: Thu Mar 24, 2016 7:14 am

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby DK7OB » Tue Dec 05, 2017 8:06 am

Just tried your websdr on my smart phone (since I'm at work and company firewall blocks non standard ports) and it worked fine. Heard a EA7 station on 40m SSB. Nice!

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g1hbe
Posts: 330
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby g1hbe » Tue Dec 05, 2017 8:35 am

Phil.

I don't listen much above 160 m these days, but I think the upper roll-off must be pretty slow as MW and 160 both seem just as lively as ever.

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Andy

vk7jj
Posts: 122
Joined: Thu Mar 02, 2017 9:56 am

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby vk7jj » Wed Dec 06, 2017 5:38 am

DK7OB wrote:Just tried your websdr on my smart phone (since I'm at work and company firewall blocks non standard ports) and it worked fine. Heard a EA7 station on 40m SSB. Nice!


Excellent.

Did a bit of fine tuning:
- increased the dynamic range of the waterfall and reset it's default level
- removed audio and FFT compression which improved the fidelity of audio and waterfall
- increased the sample rate. RF receive bandwidth is now around 6.9MHz to 7.4MHz

p.

/edit
- restored the audio and FFT compression, unfortunately the difference in internet network bandwidth of compressed to uncompressed is 200kbs v 1.3mbs

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vk7jj
Posts: 122
Joined: Thu Mar 02, 2017 9:56 am

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby vk7jj » Wed Dec 06, 2017 5:43 am

g1hbe wrote:I don't listen much above 160 m these days, but I think the upper roll-off must be pretty slow as MW and 160 both seem just as lively as ever.


Hi again Andy, I must try your approach, extending the bottom rolloff downwards so as to preserve general HF operation is all I've done. Thanks for your comments and input.

Regards,

p.

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Sasan
Posts: 120
Joined: Sat Jun 27, 2015 1:15 am
Location: Berlin

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby Sasan » Tue Dec 19, 2017 6:06 pm

Well in my case RSP1A is better than RSP2.
As I've already posted here (http://www.sdrplay.com/community/viewto ... f=7&t=2797) about my internal noise issues, I only have one such spur on RSP1A, but two on RSP2 !



RSP2 without any antenna attached on CubicSDR on a MacBook: (I've the same situation in other harmonics of these frequencies, like near the 40m band)

Image

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DF2HF, NM9A, EP2C

Sasan
Posts: 120
Joined: Sat Jun 27, 2015 1:15 am
Location: Berlin

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby Sasan » Tue Dec 19, 2017 6:28 pm

More info about my above post:
1- I'm sure a lot of you already know: changing the IF mode, changes these frequencies;
2- In Zero-IF mode, these are my spurs on RSP2:

2.297MHZ , 2.326MHZ
4.599MHZ, 4.658MHZ
6.906MHZ, 6.993MHZ
9.187MHZ , 9.300 MHZ
and on and on. These "pairs" are only visible below 16MHZ. There are other spurs on higher frequencies but they're not "pairs"

On RSP1A with Zero-IF:
2.519MHZ , 5,030, 7.533 , etc

These numbers probably will change with time/temperature but I didn't test that.

P.S: These spurs do not interfere with my daily experience and I can safely ignore them. But investigating the root cause and being able to attenuate them in future versions would be good.

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DF2HF, NM9A, EP2C

DK7OB
Posts: 65
Joined: Thu Mar 24, 2016 7:14 am

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby DK7OB » Sat Dec 23, 2017 10:31 am

Just for laughs I show my Hammy Hambone solution for the spur in the 40m band. It's a 47 Ohms 1206 SMD resistor connected to 5V and glued to the offending chip. The ~0.5 W dissipation creates enough heat to move the spur down to 6.92 MHz.

Merry Christmas and a happy new year!
2017-12-23_14-06-20_v1.jpg
2017-12-23_14-06-20_v1.jpg (84.38 KiB) Viewed 2301 times

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vk7jj
Posts: 122
Joined: Thu Mar 02, 2017 9:56 am

Re: RSP1A: wobbling spurs around 2.335MHz * n

Postby vk7jj » Sun Dec 24, 2017 2:13 am

DK7OB wrote:Just for laughs I show my Hammy Hambone solution for the spur in the 40m band. It's a 47 Ohms 1206 SMD resistor connected to 5V and glued to the offending chip. The ~0.5 W dissipation creates enough heat to move the spur down to 6.92 MHz.

Merry Christmas and a happy new year!
2017-12-23_14-06-20_v1.jpg


Good one!

Have a good holiday break, everyone.

Phil

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