Hi all,
Here is an update about a preselector frontend board on which we're working right now. Attached is an updated schematics of the board and 3D view of the board itself and the proposed way of mounting it to the main board.
The github repository still contain an older revision of the schematics - I will update it a bit later when I get full project files from Andrey Sviyazov. https://github.com/chemeris/umtrx-schematics/tree/master/umtrx-v2-rxsel
We would appreciate all constructive comments about the board design - from both RF and mechanical points of view.
-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
Andrey,
Could you remind me what the IF after the preselector?
A comment from Harald from IRC: I hope the IF is not above 380 MHz, because 380...400 MHz is the European emergency services band (strong tetra BTS, ...)
On Thu, Aug 23, 2012 at 11:28 PM, Alexander Chemeris alexander.chemeris@gmail.com wrote:
Hi all,
Here is an update about a preselector frontend board on which we're working right now. Attached is an updated schematics of the board and 3D view of the board itself and the proposed way of mounting it to the main board.
The github repository still contain an older revision of the schematics - I will update it a bit later when I get full project files from Andrey Sviyazov. https://github.com/chemeris/umtrx-schematics/tree/master/umtrx-v2-rxsel
We would appreciate all constructive comments about the board design - from both RF and mechanical points of view.
-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
Hi Alexander,
As far as I understand, the IF frequency should be 360 MHz as the UmSEL uses the TB0130A IF SAW filter. Its center frequency is 360 MHz.
By the way, why do you say it would be a problem if IF was above 380 MHz ? Because of interferences ? In this case, would it still be problem if we install the UmTRX + UmSEL boards inside an enclosure ?
Best regards.
Jean-Samuel. :-)
On Fri, Aug 24, 2012 at 5:31 AM, Alexander Chemeris < alexander.chemeris@gmail.com> wrote:
Andrey,
Could you remind me what the IF after the preselector?
A comment from Harald from IRC: I hope the IF is not above 380 MHz, because 380...400 MHz is the European emergency services band (strong tetra BTS, ...)
On Thu, Aug 23, 2012 at 11:28 PM, Alexander Chemeris alexander.chemeris@gmail.com wrote:
Hi all,
Here is an update about a preselector frontend board on which we're working right now. Attached is an updated schematics of the board and 3D view of the board itself and the proposed way of mounting it to the main board.
The github repository still contain an older revision of the schematics - I will update it a bit later when I get full project files from Andrey Sviyazov. https://github.com/chemeris/umtrx-schematics/tree/master/umtrx-v2-rxsel
We would appreciate all constructive comments about the board design - from both RF and mechanical points of view.
-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
On Fri, Aug 24, 2012 at 12:34 PM, Jean-Samuel Najnudel - BJT PARTNERS SARL jsn@bjtpartners.com wrote:
Hi Alexander,
As far as I understand, the IF frequency should be 360 MHz as the UmSEL uses the TB0130A IF SAW filter. Its center frequency is 360 MHz.
Ok, thanks.
By the way, why do you say it would be a problem if IF was above 380 MHz ? Because of interferences ? In this case, would it still be problem if we install the UmTRX + UmSEL boards inside an enclosure ?
Well, the original question was from Harald, but the concern was with interference, yes.
I think it depends on the type of enclosure we use. Andrey should be able to comment here.
Hi all!
As far as I understand, the IF frequency should be 360 MHz as the UmSEL uses
the TB0130A IF SAW filter. Its center frequency is 360 MHz.
Yes, IF freq can be 360MHz (TB0130A) or 400MHz (TB0448A), matching components there is for both variants (C32/C38, C46/C51).
By the way, why do you say it would be a problem if IF was above 380 MHz
?
Because of interferences ? In this case, would it still be problem if we install the UmTRX + UmSEL boards inside an enclosure ?
Well, the original question was from Harald, but the concern was with interference, yes.
I thought about these well known problems like strong mirror (image) freq's with their interfer's, direct passthrough, LO-ANT emission and so on. So, month ago I made measures of RF SAW filter TA1003A (see pics here). Actually, I chose quite typical method - additional highpass filter (Z6 - HFCN-740+). I hope it can help to avoid most of those low-frequencies problems. It will be much better if Taiyo Yuden RF filters would be used (those filters also known as Fujitsu brand).
I think it depends on the type of enclosure we use. Andrey should be able to comment here.
Yes, of course, tower-mounted enclosures should be not only IP65, but also EMI isolated.
Best regards, Andrey Sviyazov.
BTW,
Are you using upper or lower image ?
Let's say bringing 900 to 400 you can use LO of 1.3 GHz or of 500 MHz right ?
With 1.3 GHz you will get images from 1.7 GHz With 500 MHz you will get images from 100 MHz (FM Radio !!!)
Cheers,
Sylvain
I think to use 550mhz in case of 360 mhz IF. So image will be around 190 mhz, but here also there are very strong TV and trank radios.
Best regards, Andrey Sviyazov. (Sent from my mobile client) 24.08.2012 18:08 пользователь "Sylvain Munaut" 246tnt@gmail.com написал:
BTW,
Are you using upper or lower image ?
Let's say bringing 900 to 400 you can use LO of 1.3 GHz or of 500 MHz right ?
With 1.3 GHz you will get images from 1.7 GHz With 500 MHz you will get images from 100 MHz (FM Radio !!!)
Cheers,
Sylvain
Alexander, could you please push through my letter? Stopped due to over 1MB :(
Best regards, Andrey Sviyazov.
I've discarded those e-mails because of their size and instead I've checked in those files into the git: https://github.com/chemeris/umtrx-schematics
Your comments are welcome.
On Fri, Aug 24, 2012 at 10:12 PM, Andrey Sviyazov andreysviyaz@gmail.com wrote:
Here zip with PCB and Gerbers. That's all folks ;)
Best regards, Andrey Sviyazov.
2012/8/24 Andrey Sviyazov andreysviyaz@gmail.com
Hi all.
Here zip with all project files include PDF and BOM for GSM900 assembly variant. PCB and Gerber will be in the next letter.
Best regards, Andrey Sviyazov.
2012/8/24 Andrey Sviyazov andreysviyaz@gmail.com
I think to use 550mhz in case of 360 mhz IF. So image will be around 190 mhz, but here also there are very strong TV and trank radios.
Best regards, Andrey Sviyazov. (Sent from my mobile client)
24.08.2012 18:08 пользователь "Sylvain Munaut" 246tnt@gmail.com написал:
BTW,
Are you using upper or lower image ?
Let's say bringing 900 to 400 you can use LO of 1.3 GHz or of 500 MHz right ?
With 1.3 GHz you will get images from 1.7 GHz With 500 MHz you will get images from 100 MHz (FM Radio !!!)
Cheers,
Sylvain
And one question from me - wouldn't it be better to move "CH1" and "CH2" label to outside of the boxes? If we decide to put actual EMI shields, labels will be hidden.
On Sat, Aug 25, 2012 at 3:24 PM, Alexander Chemeris alexander.chemeris@gmail.com wrote:
I've discarded those e-mails because of their size and instead I've checked in those files into the git: https://github.com/chemeris/umtrx-schematics
Your comments are welcome.
On Fri, Aug 24, 2012 at 10:12 PM, Andrey Sviyazov andreysviyaz@gmail.com wrote:
Here zip with PCB and Gerbers. That's all folks ;)
Best regards, Andrey Sviyazov.
2012/8/24 Andrey Sviyazov andreysviyaz@gmail.com
Hi all.
Here zip with all project files include PDF and BOM for GSM900 assembly variant. PCB and Gerber will be in the next letter.
Best regards, Andrey Sviyazov.
2012/8/24 Andrey Sviyazov andreysviyaz@gmail.com
I think to use 550mhz in case of 360 mhz IF. So image will be around 190 mhz, but here also there are very strong TV and trank radios.
Best regards, Andrey Sviyazov. (Sent from my mobile client)
24.08.2012 18:08 пользователь "Sylvain Munaut" 246tnt@gmail.com написал:
BTW,
Are you using upper or lower image ?
Let's say bringing 900 to 400 you can use LO of 1.3 GHz or of 500 MHz right ?
With 1.3 GHz you will get images from 1.7 GHz With 500 MHz you will get images from 100 MHz (FM Radio !!!)
Cheers,
Sylvain-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
I hope screening is not really required. Anyway, you need only connectors labels if all covered by screen.
Best regards, Andrey Sviyazov. (Sent from my mobile client) 25.08.2012 15:43 пользователь "Alexander Chemeris" < alexander.chemeris@gmail.com> написал:
And one question from me - wouldn't it be better to move "CH1" and "CH2" label to outside of the boxes? If we decide to put actual EMI shields, labels will be hidden.
On Sat, Aug 25, 2012 at 3:24 PM, Alexander Chemeris alexander.chemeris@gmail.com wrote:
I've discarded those e-mails because of their size and instead I've checked in those files into the git: https://github.com/chemeris/umtrx-schematics
Your comments are welcome.
On Fri, Aug 24, 2012 at 10:12 PM, Andrey Sviyazov andreysviyaz@gmail.com wrote:
Here zip with PCB and Gerbers. That's all folks ;)
Best regards, Andrey Sviyazov.
2012/8/24 Andrey Sviyazov andreysviyaz@gmail.com
Hi all.
Here zip with all project files include PDF and BOM for GSM900 assembly variant. PCB and Gerber will be in the next letter.
Best regards, Andrey Sviyazov.
2012/8/24 Andrey Sviyazov andreysviyaz@gmail.com
I think to use 550mhz in case of 360 mhz IF. So image will be around 190 mhz, but here also there are very strong
TV
and trank radios.
Best regards, Andrey Sviyazov. (Sent from my mobile client)
24.08.2012 18:08 пользователь "Sylvain Munaut" 246tnt@gmail.com написал:
BTW,
Are you using upper or lower image ?
Let's say bringing 900 to 400 you can use LO of 1.3 GHz or of 500 MHz right ?
With 1.3 GHz you will get images from 1.7 GHz With 500 MHz you will get images from 100 MHz (FM Radio !!!)
Cheers,
Sylvain-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru
-
Alexander Chemeris -
Andrey Sviyazov -
Jean-Samuel Najnudel - BJT PARTNERS SARL -
Sylvain Munaut