Hacking the Goscam GP-622RA 2.4GHz receiver module

Stuff I am working on
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Daniel Wee
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Hacking the Goscam GP-622RA 2.4GHz receiver module

Post by Daniel Wee » Wed 15 Jul 15 2009 10:23 am

The 2.4GHz video receivers Mark uses employs the GP-622RA receiver modules. This has been shown to have quite good sensitivity thus far and we want to see if there is any way by which we can improve this performance further.
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Daniel
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Daniel Wee
Site Admin
Posts: 2084
Joined: Wed 25 Feb 25 2009 8:00 pm

Re: Hacking the GP-622RA 2.4GHz receiver module

Post by Daniel Wee » Wed 15 Jul 15 2009 11:02 am

The breakdown of the key active component parts are as follows:-

HS153SN-J - 8-bit MCU from EMC or Elan
SL1461SAB - Video IF IC from Zarlink
E07SL - PLL IC from Fujitsu
U2860B - FM stereo demodulator
F480-1 - 480MHz SAW filter BW:21MHz(-1.5dB), IL:18dB
P5 - BFG425W NPN RF transistor

Daniel
Attachments
Philips-BFG425W.pdf
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Atmel-U2860B doc4794.pdf
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Fujitsu-MB15E07SL.pdf
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Zarlink-SL1461.pdf
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Elan-EM78P153S.pdf
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Daniel Wee
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Posts: 2084
Joined: Wed 25 Feb 25 2009 8:00 pm

SAW filter

Post by Daniel Wee » Wed 15 Jul 15 2009 12:20 pm

The IF frequency appears to be 480MHz. Typical video bandwidth is around 15MHz in total. The SAW filter used, however, has a bandwidth of 21MHz so in theory we could improve the S/N ratio by using a narrower filter. We can also try using a filter with a lower insertion-loss. It is unclear at this point what how the ripple affects actual video performance.
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The thing here is that wider bandwidths actually make for sharper pictures. By narrowing the filter, the definition starts to look softer. At the end of the day, a fully modulated video signal still occupies around 21MHz so we are stuck with this bandwidth. The key now is to see if we can get lower IL filters.

Daniel

Daniel Wee
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Posts: 2084
Joined: Wed 25 Feb 25 2009 8:00 pm

Re: Hacking the Goscam GP-622RA 2.4GHz receiver module

Post by Daniel Wee » Wed 12 Aug 12 2009 11:07 pm

Okay, so I decided to pull the SAW filter from this module. This was quite difficult as the ground plane was shunting away heat as fast as we can apply it.
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This filter and others like it have typical IL of around 20dB or more. The trick then is to find a better filter, one with around 4-5dB of IL which translates to a 16dBm improvement in sensitivity.

Daniel
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HPF-NMF480-1.pdf
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Daniel Wee
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Posts: 2084
Joined: Wed 25 Feb 25 2009 8:00 pm

Re: Hacking the Goscam GP-622RA 2.4GHz receiver module

Post by Daniel Wee » Wed 12 Aug 12 2009 11:52 pm

Forgot to post the datasheet for the modules.

Daniel
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Manual of 622R.pdf
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