Author Topic: Interface  (Read 4545 times)

VE3ZI

  • Newbie
  • *
  • Posts: 14
    • View Profile
Interface
« on: 2011-05-31, 02:14:14 »
Please excuse me if these questions have been answered before, but I really have tried to RTFM...

I can't find a definitive level for audio input and output at each end of the link, only in unreferenced dBs. At the remote end I am using an Icom transceiver and want to connect to the accessory socket - which has a vague 'few hundred mV' (high impedance) in and out. It would be nice if I could set the levels to use the highest possible dynamic ranges.

I think that the internal Aux/Mic configuration header just defines which connections go to which pins on the Aux/Mic connector? So it should be (pin numbering as if header was an IC):

Pin 1 (control) - audio output from remote receiver;  Pin 1 (radio) - audio input from receiver
Pin 2 (control) - 8V (9V) to power local microphone; Pin 2 (radio) - power on - not sure what power???
Pin 3 (control) - data from remote radio;                 Pin 3 (radio) - data from radio <for detachable front panel radio>
Pin 4 (control) - ptt from local microphone              Pin 4 (radio) - ptt to radio
Pin 5 (control) - audio from local microphone           Pin 5 (radio) - to radio microphone input
Pin 6 (control) - data to remote radio                     Pin 6 (radio) - data to radio <for detachable front panel radio>
Pin 7 (control) - GND                                           Pin 7 (radio) - GND
Pin 8 (control) - mic GND                                     Pin 8 (radio) - mic GND
Pin 9 (control) - I think related to connecting/disconnecting the link by grounding this pin?

My application is improving the operation of an existing remote controlled station. Specifically, to allow audio to be sent over the ethernet link (rather than a 440MHz radio), and to improve the CW keying. The remote station is 14km away over a 900MHz ethernet radio link. The link is usually quite fast (~1.5Mbs simultaneously in both directions), but sometimes slows, I think due to interference.

I'm sure there will be any number of other questions, but answers to these would be a great start.

Thanks

73 Roger
VE3ZI



va3mw

  • Jr. Member
  • **
  • Posts: 42
    • View Profile
    • Email
Re: Interface
« Reply #1 on: 2011-05-31, 16:28:02 »
Hi Roger

Wow, I wish I was closer to you so I could help.  I just got my remote working from the house to the cottage. 

Can I measure anything for you?

Mike va3mw

sm2o

  • Administrator
  • Hero Member
  • *****
  • Posts: 3007
    • View Profile
    • sm2oan
    • Email
Re: Interface
« Reply #2 on: 2011-05-31, 21:23:01 »
Hi

The mic amplifier and codec gain is adjust to fit most microphones I don't think you need to change it. But you can not use low level rx-audio without modification. The Rx audio input impedance is 50 ohm and levels are set for using speaker output from the radio. If you must use the low level output from the radio, you must remove the big 100R resistors from the Radio-RRC pcb.

73 de mike

VK3ZFS

  • Newbie
  • *
  • Posts: 18
    • View Profile
Re: Interface
« Reply #3 on: 2011-06-01, 10:59:56 »
Im curious, what are the relative levels from codec input to output and vice-versa, it would be better to say input 0dBr output -6dBr for example, it would be much more easy to set levels, im assuming the pre-amp is used only for low level mic, if you wish to use at line level (0dB) you would have the pre-amp off?

VE3ZI

  • Newbie
  • *
  • Posts: 14
    • View Profile
Re: Interface
« Reply #4 on: 2011-06-02, 00:47:24 »
Thanks for the information.

I can see why you made the units interface directly to a loudspeaker output as it is obviously better for those radios with detachable front panels. If you were ever to remake the PCB it would be nice to have the 50R load(s) jumper selected.  :)

Whilst it would be very straightforward to disconnect the resistors I don't want to start hacking around a brand new unit, so I will build a small LS amplifier for the remote site. I don't want to use the remote radio's internal LS amplifier as I am bound to leave the volume set at zero when I am there leading to hair pulling and cursing.

It would still be good to have detailed interface specs somewhere in the User Manual - it just makes it so much easier for slightly non-standard applications.

Am I correct in my listing of the functions of the internal header?

Thanks

73 Roger
VE3ZI