UmTRX performance questions

Andrey Sviyazov andreysviyaz at gmail.com
Sun Mar 10 19:20:31 UTC 2013


Hi Joel.

> 2. What is the power output in dbm of your umtrx?
>>
> After fixing this issue<https://code.google.com/p/umtrx/issues/detail?id=41&can=1&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary%20Modified>I measured + 20 dBm for 900 MHz band and +17 dBm for 1800.
>
> I will be testing this UMTRX with a DCS amp with 10 dBM input. Just to be
> sure, I just need to adjust attenuation to at least 7 dBM and 8 probably to
> avoid clipping the RF amp as below:
>
> GSM.Radio.PowerManager.MaxAttenDB 8
> GSM.Radio.PowerManager.MinAttenDB 0
>

Please explain more what att do you try to use and what clipping do you
mean (may be 1dB gain compression) ?
Anyhow, you can easy adjust output signal of UmTRX by using --gain in case
of UHD TX control.
Also can be used TXVGA2 gain in case of direct LMS registers control via
Python scripts.


> Is using an LNA with BPF advisable with your UMTRX?
>
Yes of course.
External LNA and duplexer or band pass filter should be used for better NF
performance.


>
> What is the operating temperature of your UMTRX as I want to make sure the
> HD case I am using for testing is good enough. I installed a small fan and
> so far temperature is around 40 deg C.
>

You can find on the board FUN2 control IC (U35)
MAX6665ASA45<http://datasheets.maximintegrated.com/en/ds/MAX6665.pdf>
.
So, at the PCB temperature +45'C FUN2 must start to cooling.
And if you do not use FAN2 (or broken) then this IC will switch off UmTRX
at temperature 45+30=75'C.
Low temperature limit is minus 40'C due to industrial components (is not
tested 100% in production).


> The LEDs are on the board and I may want to solder some LEDs to monitor
> status, where on the board can I terminate the power for LEDs?
>

You can use any DC-DC output higher 2V through current limiting resistor.
Pleas refer to datasheet of your LED's type to find proper resistor value.


>
> On Tue, Mar 5, 2013 at 10:16 AM, Andrey Sviyazov <andreysviyaz at gmail.com>wrote:
>
>> Hi Joel.
>>
>> On Fri, Feb 22, 2013 at 6:28 PM, joel yabut <joel at jointventure.com>
>> wrote:
>>
>>> > May i know the following specs
>>> > 1. What is the tx and rx isolation of umtrx?
>>>
>> Not yet measured and unfortunately there are no info from Lime Micro.
>>
>> > 2. What is the power output in dbm of your umtrx?
>>>
>> After fixing this issue<https://code.google.com/p/umtrx/issues/detail?id=41&can=1&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary%20Modified>I measured + 20 dBm for 900 MHz band and +17 dBm for 1800.
>>
>>
>>>
>>> > 3. How is the lna on the rx input and is an external lna and bpf
>>> > recommended?
>>>
>>> For Fairwaves 10W base stations we're developing UmSEL, which has
>>> channel filter and an additional LNA. For the use without amplifier
>>> you don't need any additional filters or LNAs.
>>>
>>> > 4. What is the main advantage of umtrx compared to usrp by ettus?
>>>
>>> If you want to use it for GSM, then it's cheaper and gives you
>>> dual-channel support.
>>>
>>> --
>>> Regards,
>>> Alexander Chemeris.
>>> CEO, Fairwaves LLC / ООО УмРадио
>>> http://fairwaves.ru
>>>
>>> Best regards,
>> Andrey Sviyazov.
>>
>
>
>
> --
> Mother Ignacia Avenue corner Scout Rallos St.
> Quezon City, Metro Manila, Philippines
>
>
Best regards,
Andrey Sviyazov.
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