Selectivity improvement solutions proposal for UmTRX

Andrey Sviyazov andreysviyaz at
Mon Mar 19 10:15:46 UTC 2012

Hi all!

First of all, I forgot one question regarding the IF SAW filters.
TB0130A has at least 10dB higher rejection at 0.6-0.9MHz offset band (65dB)
than TB448A (55dB), and 20dB higher rejection at 0.9-1.5MHz offset band
(75dB instead of 55dB).
Moreover, TB0130A has more flatter and wider passband, approx 300kHz at
0.5dB instead of 250kHz for TB448A, it is better because of this type SAW
has thermal drift approx +-32 kHz for +-50'C relative to +25'C.
In other hand, TB448A has better group delay ripples, but I don't how it
critical for GMSK, and I'm sure that symmetry law more important.
Also we can adjust central IF for 3-5 temperature points, but in this case
we need to add thermal measurements, and let we try to avoid it.

Best regards,
Andrey Sviyazov.

19 марта 2012 г. 12:30 пользователь Andrey Sviyazov
<andreysviyaz at>написал:

> Hi Alexander.
> Actualy I don't know side-type connectors for cable.
> I suggested you PCB side connector (like PCI) for debugging only.
> Moreover, there are a lot SMD connectors for IDC flat cable, BHS-10 for
> example.
> Best regards,
> Andrey Sviyazov.
> 19 марта 2012 г. 10:14 пользователь Alexander Chemeris <
> alexander.chemeris at> написал:
> Andrey,
>> 2012/3/19 Andrey Sviyazov <andreysviyaz at>:
>> > 5) Regarding connectors, I only can suggest to use the two angle
>> SMA-female
>> > connectors for outputs which will stick out through the panel of the
>> housing
>> > (as you can use the angle SMA connectors, but for GPS and CLK_I/O on the
>> > UmTRX board). At the same time for the internal 4 connectors we can use
>> some
>> > cheap like U.FL and cable assemblies U.FL-MCX or  U.FL-U.FL. Signal
>> > CLK_26MHz,  6.5VDC, SPI and Switch controls will go via IDC control
>> > connector.
>> IDC connectors on a UmTRX and on a RF board will be connected with a
>> flat ribbon cable?
>> Why don't you want to use a side connector?
>> --
>> Regards,
>> Alexander Chemeris.
>> CEO, Fairwaves LLC / ООО УмРадио
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