[hpsdr] Janus Rev B Update

[Phil Harman]

Helmut,

I have the prototype Janus breadboard running on my bench - it runs full 
duplex fine. The PWM D/A converters in the FPGA work just fine also and no 
reason to think this wont be a great satellite rig. If I get time over the 
weekend I will post the latest draft of the protocol that we are using over 
the USB - from that you will see that full duplex is not a problem.

Phil...
----- Original Message ----- 
From: "vk4str" <vk4str at netspace.net.au>
To: "Lyle Johnson" <kk7p at wavecable.com>
Cc: <links at hpsdir.org>; <hpsdr at hpsdr.org>
Sent: Saturday, May 13, 2006 7:29 PM
Subject: Re: [hpsdr] Janus Rev B Update


> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Lyle,
>
> Nice job! However, as I have discussed before with Phil_H, this design
> may not be full duplex capable, ie useable to work a satellite
> transponder. I understand that PWM has certain limitations, please
> correct me if I am wrong.
>
> The AK5394A is used for RX and the processed audio is output on the
> speaker or headphone of the TLV320AIC23B.
>
> The TX audio is fed to the MIC input of the TLV with the only TX output
> option being PWM. The Line-out cannot be used if the speaker is in use.
>
> Would a DAC for TX output not be a better option? I somehow dont trust
> that the PWM option will be satisfactory for TX.
>
> 73, Helmut VK4STR
>
>
> Lyle Johnson wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> The untested Janus Rev B design is ready for review.  It may still have
>> some significant changes pending results of testing.  The AK5394A ADC
>> sample chip is at FedEx enroute to the Land of Oz for Phil H to connect
>> and test.
>>
>> In the meantime, you might like to see what's up with the proposed 
>> design.
>>
>> The basic changes are:
>>
>> 1) ADC changed from Cirrus CS5381 to AKM AK5394A.  There are numerous
>> minor changes that resulted from this.  The input op amps are shown as
>> LT parts, but many other less expensive, pin compatible parts exist for
>> those of you who like to experiment.
>>
>> 2) 1-wire EEPROM added for ID and configuration.
>>
>> 3) PCB layout cleanup.
>>
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