This email is to verify 2 items:
A) As per emails (1) and (2) below, in order to use the set_auto_tr()
feature on RFX boards, I need to stall the TX path somehow since -
any- input on the TX path will result in no RX (even all 0’s).
B) After searching through gnuradio-core/src/lib, I find no
“gr_stall” or similar. Does this block exist anywhere, and if not,
is there a simple way around it or should I just write the block
(it’s not difficult, but why reinvent the wheel)? Or does someone
have an implementation that I can leverage?
The “set_auto_tr()” method sounds from my reading to be a great way
to go, but the examples I’ve found in gnuradio-examples instead use
“subdev.set_enable()” instead … which from reading through the GNU
Radio email archives is quite a bit slower than the former. Thus my
wondering if anyone is using the former, and if so, how?
Thanks! - MLD
1: < discuss-gnuradio (date)
msg00233.html >
From: Eric B. [email protected]
Date: September 23, 2006 6:30:33 PM EDT
To: Bdale Garbee [email protected]
Cc: [email protected]
Subject: Re: [Discuss-gnuradio] USRP push-to-talk?
[snip]
(2) Take advantage of the hooks for “auto T/R switching”.
The RFX boards use this, but it’s ignored by the basic tx and rx.
[snip]
all this depends on your application “stalling” the
transmit path unless it’s got something to do. I seem to recall
that somebody built a “stall” block, but in looking through “general”,
I don’t see it. Does this sound familiar to anyone? Johnathan,
weren’t you looking at this? (It might have been a mute/squelch
block, with the same idea).
As I recall it was going to work like this:
stall = gr.stall(sizeof_item)
…
stall.set_stall(True) # Causes the block to consume all input,
# but produce no output
…
stall.set_stall(False) # block copies input to output, producing
# and consuming in the normal way
Then your “push to talk” button would just call the set_stall method
as appropriate.
2: < discuss-gnuradio (date)
msg00234.html >
From: Eric B. [email protected]
Date: November 14, 2006 10:34:56 PM EST
To: [email protected]
Cc: gnuradio mailing list [email protected]
Subject: Re: [Discuss-gnuradio] Re: USRP push-to-talk?
On Mon, Nov 13, 2006 at 09:39:30PM -0500, [email protected] wrote:
[snip]
Also, in a previous e-mail you suggested using Auto T/R in a push-
to-talk case.
Would this help in the situation where I want just a half-duplex
system? My
understanding of the Auto T/R says no, but that doesn’t mean that
I’m right
If you stall the transmit pipeline unless the user is pressing the PTT
button, then Auto T/R is what you want. In that case, the receiver is
always running, but the transmitter is only producing output when it’s
not stalled.
If Tom’s around, check with him. He and I talked about ways to do this.
Eric