headers
'Zaba' OH1ZAA | 3 Aug 10:00
Picon

Linrad gain programming (hardware side) / Linrad-TX


Linrad is actually a quite remarkable system regarding gain control 
as it seems
to be able to cope with most situations without need to change the hardware
configuration either with attenuators or any AGC-action. At least in 
my private
50 MHz experiments with a simple I/Q-direct receiver I have never come across
a signal level situation where any change in the basic gain layout was needed.

Just in case more dynamic range is needed in Linrad hardware or other 
I/Q-systems
I would like to point to a new product by National Semiconductor that 
will allow a
precise adjustment in gain in two or more channels, if needed. The 
LMP 8100 allows
24 dB gain regulation with 0.03% precision. Close gain tracking 
between channels is
beneficial in (multiple) I/Q-systems as there will be no need for 
re-calibration when
jumping between gain settings. Its noise performance is very similar 
to fixed gain
amplifiers and its slew rate is excellent with a 33 MHz unity gain bandwidth.

http://www.national.com/pf/LM/LMP8100.html   (with a link to .PDF-specs)

It is good to see the new development on the Linrad transmit side 
with lir02-36.

http://www.nitehawk.com/sm5bsz/linuxdsp/lintx.htm
(Continue reading)

Permalink | Reply | 0 comments |
headers
Leif Asbrink | 3 Aug 10:58

Re: Linrad gain programming (hardware side) / Linrad-TX

Hi Zaba,

> Linrad is actually a quite remarkable system regarding gain control 
> as it seems
> to be able to cope with most situations without need to change the hardware
> configuration either with attenuators or any AGC-action. At least in 
> my private
> 50 MHz experiments with a simple I/Q-direct receiver I have never come across
> a signal level situation where any change in the basic gain layout was needed.
Good! 

> Just in case more dynamic range is needed in Linrad hardware or other 
> I/Q-systems
> I would like to point to a new product by National Semiconductor that 
> will allow a
> precise adjustment in gain in two or more channels, if needed. The 
> LMP 8100 allows
> 24 dB gain regulation with 0.03% precision. Close gain tracking 
> between channels is
> beneficial in (multiple) I/Q-systems as there will be no need for 
> re-calibration when
> jumping between gain settings. Its noise performance is very similar 
> to fixed gain
> amplifiers and its slew rate is excellent with a 33 MHz unity gain bandwidth.
> 
> http://www.national.com/pf/LM/LMP8100.html   (with a link to .PDF-specs)
Actually I do not think this is needed. There should be no reason to 
change the  gain in the baseband, the amplifiers after the I/Q mixers
should always be optimised for the best possible dynamic range.
In case more dynamic range is needed, the variation should be applied
(Continue reading)

Permalink | Reply | 0 comments |
headers
Giancarlo Moda | 4 Aug 20:01
Picon
Favicon

NOT LINRAD - I0CG NEW AD9912 DDS

Hi all,
You may recall my note regarding the expected good
results on low spurs using the Analog Devices AD9912
1GHz DDS.
Well, my good friend Giuliano, I0CG, (of AD9951 DDS
fame) has now experimented enough with this new DDS
chip and done some measurements with interesting
results.

His comments are:

“My laboratory tests demonstrate that spurious
performance and frequency extension are superior to
all others actual DDS, including the AD9951.
In a few words … This new AD9912 DDS is the best
solution available today for amateur radio
applications” 

You may visit his web site and see spectrum analyzer
screen shots and comparison with his old AD9951 DDS
design: 

1) AD9912 with 190 MHz output ( Clock 1 GHz )Analyzer
span= 200 MHz

2) old AD9951 with158 MHz output ( clock 500 MHz
)Analyzer span= 200 MHz

3) AD9912 Frequency extension test: 400 MHz output (
clock 1 GHz )Analyzer span= 500 MHz
(Continue reading)

Permalink | Reply | 0 comments |
headers
David Garnier | 5 Aug 03:22
Picon

Re: NOT LINRAD - I0CG NEW AD9912 DDS

Hello,

I wonder how difficult getting pre-production parts from AD is these days???

http://www.analog.com/en/prod/0,,770_843_AD9912,00.html

Dave Garnier - wb9own

Giancarlo Moda wrote:
> Hi all,
> You may recall my note regarding the expected good
> results on low spurs using the Analog Devices AD9912
> 1GHz DDS.
> Well, my good friend Giuliano, I0CG, (of AD9951 DDS
> fame) has now experimented enough with this new DDS
> chip and done some measurements with interesting
> results.
>
> His comments are:
>
> “My laboratory tests demonstrate that spurious
> performance and frequency extension are superior to
> all others actual DDS, including the AD9951.
> In a few words … This new AD9912 DDS is the best
> solution available today for amateur radio
> applications” 
>
> You may visit his web site and see spectrum analyzer
> screen shots and comparison with his old AD9951 DDS
> design:
(Continue reading)

Permalink | Reply | 0 comments |
headers
Joe Taylor | 8 Aug 16:27
Picon
Favicon

Re: MAP65

Hi Francesco,

When I receive an email from "root", I always know that it 
comes from a Linrad user!

I hope you do not mind if I copy this reply to the Linrad 
reflector.  I think your question and my answer may be 
interesting to others.

root wrote:
> Hello Joe, a simple question.
> I use Linrad by long and long time, but 
> with only "H" pol antenna. My question is
> may i use MAP65?

Yes!

> And if the answer is positive, may i use it with results,
> on my Notebook with the AC97 soundblaster and without wire (cross cable)
> connection, right as i do today, where i have the main PC with Ubuntu
> and Linrad and the notebook with the wsjt. They are only connected via
> sound blaster.

As I understand it, you are connecting Linrad's audio output 
to audio input on the Notebook, using an audio cable.  WSJT 
runs on the Notebook, and gives you a bandwidth of something 
like 2-4 kHz, right?

This procedure will not work for MAP65, because MAP65 wants 
to have access to the full 90 kHz bandwidth available inside
(Continue reading)

Permalink | Reply | 0 comments |
headers
Joe Taylor | 8 Aug 17:57
Picon
Favicon

Linrad, MAP65, and SDR-IQ

Hi Leif and all,

I have been thinking about ways to make MAP65 available to 
those using the SDR-IQ (or SDR-14).  Last evening I re-read 
your very informative email of July 2 to Fletch, K3JYD.

As I understand it, the SDR-IQ always samples at 66.6667 MHz 
at its input.  Its on-board AD6220 digital down-converter 
divides the sample rate by a number N that is the product of 
three integers: CIC2 * CIC5 * RCF.  By reading the AD6620 
spec sheet I find that CIC2 must be in the range 2-16, CIC5 
and RCF in the range 1-32.  I think Linrad allows one to 
choose these integers, and I understand that some trade-offs 
concerning location and attenuation of spurs will be 
involved in the choice.

MAP65 presently requires an input sample rate of 96000 Hz.

The ratios 66,666,667/694 = 96061.48... and
66,666,667/695 = 95923.26... are probably "close enough", 
but they are not usable because 694 = 2 * 347 and 695 = 5 * 
139, and both 347 and 139 are prime.

So it seems that to provide a usable bandwidth of about 90 
kHz with the SDR-IQ, MAP65 must provide an option to use 
input data sampled at some new rate commensurate with 
66.6667 MHz, with an integer divisor somewhere around 700. 
The divisor must be factorable into three integers 32 or 
smaller.
(Continue reading)

Permalink | Reply | 0 comments |
headers
Francesco | 8 Aug 18:54
Picon

R: [linrad] Re: MAP65

Thank you very much Joe for your kind replay.
I need to read one more time your suggestions and see wht's for me the
simplest way
to do. Maybe the N°2.
Enjoy your vacations and see you again on eme.

Francesco,IK2DDR

-----Messaggio originale-----
Da: Linrad mailinglist [mailto:linrad@...]Per
conto di
Joe Taylor
Inviato: mercoledì 8 agosto 2007 16.27
A: Linrad mailinglist
Oggetto: [linrad] Re: MAP65

Hi Francesco,

When I receive an email from "root", I always know that it
comes from a Linrad user!

I hope you do not mind if I copy this reply to the Linrad
reflector.  I think your question and my answer may be
interesting to others.

root wrote:
> Hello Joe, a simple question.
> I use Linrad by long and long time, but
> with only "H" pol antenna. My question is
> may i use MAP65?
(Continue reading)

Permalink | Reply | 0 comments |
headers
f6dro | 9 Aug 07:01
Picon

Re: R: [linrad] Re: MAP65

Hello ,

in case SDR-IQ gets possivle to use with MAP65 , we also need to use 2 
boards with a common LO. It is possible to use an external LO on SDR-IQ , 
but a better way would be to one board LO to drive the other board , I don't 
know wether it is easily possible  to do this , I don't have board 
schematics .

73 Dom/F6DRO 

#############################################################
This message is sent to you because you are subscribed to
  the mailing list <linrad@...>.
To unsubscribe, E-mail to: <linrad-off@...>
To switch to the DIGEST mode, E-mail to <linrad-digest@...>
To switch to the INDEX mode, E-mail to <linrad-index@...>
Send administrative queries to  <linrad-request@...>
Permalink | Reply | 0 comments |
headers
Joe Taylor | 9 Aug 20:36
Picon
Favicon

Re: R: [linrad] Re: MAP65

Hi Dom,

You are right, of course, that for full xpol reception one 
would need two of the SDR-IQ, SDR-14, SDR-1000, etc., 
receivers.

SDR-IQ x 2 might be a cost-effective way to go, but as you 
say it will require a common LO feeding two boards. 
Moreover, I think something further would need to be done to 
synchronize the sampling phase on the two boards. 
Retro-fitting this to the existing boards may not be easy.

For now, I am thinking of the SDR-IQ --> Linrad --> MAP65 
combination as an attractive solution only for stations with 
single-polarization antennas.

	-- 73, Joe, K1JT

f6dro wrote:
> Hello ,
> 
> in case SDR-IQ gets possivle to use with MAP65 , we also need to use 2 
> boards with a common LO. It is possible to use an external LO on SDR-IQ 
> , but a better way would be to one board LO to drive the other board , I 
> don't know wether it is easily possible  to do this , I don't have board 
> schematics .
> 
> 73 Dom/F6DRO
> 
>
(Continue reading)

Permalink | Reply | 2 comments |
headers
Leif Asbrink | 10 Aug 12:47

Re: MAP65

Hi Dom,

> in case SDR-IQ gets possivle to use with MAP65 , we also need to use 2 
> boards with a common LO. It is possible to use an external LO on SDR-IQ , 
> but a better way would be to one board LO to drive the other board , I don't 
> know wether it is easily possible  to do this , I don't have board 
> schematics .

I think it can be done, but it will not be enough. The three decimation
steps correspond to three more mixers and they also have to be
synchronized. There are pins on the digital down converter chip for that
so it can be done.

73

Leif

#############################################################
This message is sent to you because you are subscribed to
  the mailing list <linrad@...>.
To unsubscribe, E-mail to: <linrad-off@...>
To switch to the DIGEST mode, E-mail to <linrad-digest@...>
To switch to the INDEX mode, E-mail to <linrad-index@...>
Send administrative queries to  <linrad-request@...>
Permalink | Reply | 1 comment |

Gmane