Greetings:

Homebrew online HF receiver located at approx. lat. 46.8,
lon. -92.1 is now accessible at:

http://www.cybertheque.org/homebrew/rcvr

Receiver controls are realtime, not transaction based, and
audio is also realtime, not delayed in an mpeg stream.
You will need voip (SIP) capability to hear the audio until I
am able to include a java rtp client in the web page.

If you do not already have a SIP service provider, a free
account may be created at:

http://www.iptel.org/service

The web pages will add features as the project develops and
the receiver controls will add capabilities beyond the basic
ones currently implemented.

Currently, there is no queuing of user access so a chat session
is provided on the main control page to permit waiting users
to coordinate their activities. Also, only one audio connection
at a time is currently implemented.

In the future multiple audio connections will be supported and
a user login procedure will be used to coordinate access.

Please email me at the address noted on the web pages for
questions and feedback.

Regards,

Michael
msg _at_ cybertheque _dot_ org

Looks interesting....what can you tell us about it???



"msg" wrote in message
...
Greetings:

Homebrew online HF receiver located at approx. lat. 46.8,
lon. -92.1 is now accessible at:

http://www.cybertheque.org/homebrew/rcvr

Receiver controls are realtime, not transaction based, and
audio is also realtime, not delayed in an mpeg stream.
You will need voip (SIP) capability to hear the audio until I
am able to include a java rtp client in the web page.

If you do not already have a SIP service provider, a free
account may be created at:

http://www.iptel.org/service

The web pages will add features as the project develops and
the receiver controls will add capabilities beyond the basic
ones currently implemented.

Currently, there is no queuing of user access so a chat session
is provided on the main control page to permit waiting users
to coordinate their activities. Also, only one audio connection
at a time is currently implemented.

In the future multiple audio connections will be supported and
a user login procedure will be used to coordinate access.

Please email me at the address noted on the web pages for
questions and feedback.

Regards,

Michael
msg _at_ cybertheque _dot_ org

"msg" wrote in message
Homebrew online HF receiver located at approx. lat. 46.8,
lon. -92.1 is now accessible at:

http://www.cybertheque.org/homebrew/rcvr
W3JDR wrote:
Looks interesting....what can you tell us about it???


Thanks for asking; I have not had the opportunity to yet measure
the receiver's performance (noise figure, IMD, sensitivity, etc.)
and while the design is still evolving the current leading
particulars a

1. Dual conversion from 1Hz to 75Mhz, with frontend passband
currently 140kHz to 30Mhz, traps for local FM RFI, 50 ohm nominal
input impedance, selectable RF amps.

2. 1st IF 55,850 kHz, 2nd IF 455 kHz, two filters ~2 kHz for SSB
and 5 kHz AM.

3. 1st LO is a programmable PLL with a wide variety of step sizes
and large dynamic range; I am using 2kHz steps and a range from
55,851 kHz to 131,068 kHz and a 16-bit resolution.

4. 2nd LO varactor tuned xtal osc. at 55,395 kHz with a 2kHz dynamic
range, 13-bit tuning resolution (1 Hz) using a 3-bit DAC to select
one of eight 10-bit segments tuned by a PWM through a 3rd order LPF
with 10Hz 3db bandwidth. The mcu handles the tuning of the
LOs to permit a continuous 1Hz resolution over the receiver's range.
Tempcos of components are yet to be analyzed but stability has been
quite good (within 1Hz/day). Auto calibration will be implemented
but for now tuning errors may be up to 30Hz and can be measured
against WWV which at this time of year at this QTH is heard
nearly continuously on 2.5, 5, 10 and often 15 MHz.

5. IF frequency counter, 20-bit, with selectable prescaling, used for
tuning centering, ersatz synch det. on AM, etc.

6. Product det. for CW/SSB, discrim. for FM (I anticipate implementing
FM as a selectable mode on 6m and above when I do the proper front
end changes). The tuning scheme currently centers BFO in the 2nd
IF passband for symmetrical SSB; I may add USB/LSB offsets.

7. RF section is fully enclosed in a tin faraday shield with a number
of bypassing schemes; some birdies are still introduced on the digital
I/O lines entering this can which I hope to squelch with properly
designed LPF.

8. Digital section is also fully enclosed in a tin shield and physically
separated from the RF section. I designed it around the Intel 8096
mcu; debugging and programming is facilitated by having an HMI-200 ICE.
Operating software is uploaded over an RS-232 port which also serves
as the control port for the receiver. The mcu has enough resources
to implement features such as ALE, digital modes, spectrum surveillance,
etc. but DSP features will be offloaded to dedicated processors.

9. Audio monitor output is 8 ohm with provisions for stereo and a 5000 ohm
output feeds the audio stream server.

10. Receiver and antenna are viewed as an integrated system; the antenna
is a modified Marconi matched with a 9:1 impedance ratio quadrifilar-
wound balun, isolated primary, to a 50 ohm coax feedline. The antenna
has a good ground which has a very short lead to the balun ground
in the Marconi configuration. The feedline shield is not grounded but
is continuous to the receiver chassis which currently is also not
grounded (this is very low noise). The feedline is enclosed in
plastic pipe and buried 18 inches deep in the soil from the antenna
feed to the shack further attenuating noise. The system performs
well in a very hostile RFI/EMI environment; our QTH is noted for
some of the worst QRN anywhere and the huge antenna farm for broadcasters
and public services is on a peak very nearby and causes much grief
for radios with less than excellent dynamic range/IMD and selectivity.

So far no one has tuned the receiver or made an audio connection. It is
remarkably easy to hear the audio using a SIP user agent (any voip phone
that permits dialing SIP URIs such as '. I had
suggested 'firefly' which is what I use, but it only handles numeric URIs
(so it must be registered on the callee's SIP proxy server). Instead I
recommend a version of X-Lite, which I made available at:

ftp://ftp.cybertheque.org/pub/xten

This is a Windows SIP softphone which permits dialing our SIP uri from
another network, .e.g. iptel.org. Please set up a free account at iptel.org,
download and install X-lite, configure it for the iptel.org account, and
dial the above URI to hear the audio. Access the web page to control the
receiver. At some point I hope to dispense with the need for SIP dialing
by including an RTP audio player applet in the web page (such a beast
isn't currently available, only JMF heavyweight code which is unsuitable).

Regards,

Michael

msg wrote:
"msg" wrote in message
Homebrew online HF receiver located at approx. lat. 46.8,
lon. -92.1 is now accessible at:

http://www.cybertheque.org/homebrew/rcvr
W3JDR wrote:

Looks interesting....what can you tell us about it???


Thanks for asking; I have not had the opportunity to yet measure
the receiver's performance (noise figure, IMD, sensitivity, etc.)
and while the design is still evolving the current leading
particulars a


I forgot to mention the AGC; various time constants are
selectable and signal strength is read by the ADC in the mcu
for S-meter and link-quality data.

Regards,

Michael

Very well thought out, and a fine piece of homebrewing.

The suggestion about writing a QEX article is right on. I'd sure like to
learn more.

Keep us informed

Joe
W3JDR



"msg" wrote in message
...
"msg" wrote in message
Homebrew online HF receiver located at approx. lat. 46.8,
lon. -92.1 is now accessible at:

http://www.cybertheque.org/homebrew/rcvr
W3JDR wrote:
Looks interesting....what can you tell us about it???


Thanks for asking; I have not had the opportunity to yet measure
the receiver's performance (noise figure, IMD, sensitivity, etc.)
and while the design is still evolving the current leading
particulars a

1. Dual conversion from 1Hz to 75Mhz, with frontend passband
currently 140kHz to 30Mhz, traps for local FM RFI, 50 ohm nominal
input impedance, selectable RF amps.

2. 1st IF 55,850 kHz, 2nd IF 455 kHz, two filters ~2 kHz for SSB
and 5 kHz AM.

3. 1st LO is a programmable PLL with a wide variety of step sizes
and large dynamic range; I am using 2kHz steps and a range from
55,851 kHz to 131,068 kHz and a 16-bit resolution.

4. 2nd LO varactor tuned xtal osc. at 55,395 kHz with a 2kHz dynamic
range, 13-bit tuning resolution (1 Hz) using a 3-bit DAC to select
one of eight 10-bit segments tuned by a PWM through a 3rd order LPF
with 10Hz 3db bandwidth. The mcu handles the tuning of the
LOs to permit a continuous 1Hz resolution over the receiver's range.
Tempcos of components are yet to be analyzed but stability has been
quite good (within 1Hz/day). Auto calibration will be implemented
but for now tuning errors may be up to 30Hz and can be measured
against WWV which at this time of year at this QTH is heard
nearly continuously on 2.5, 5, 10 and often 15 MHz.

5. IF frequency counter, 20-bit, with selectable prescaling, used for
tuning centering, ersatz synch det. on AM, etc.

6. Product det. for CW/SSB, discrim. for FM (I anticipate implementing
FM as a selectable mode on 6m and above when I do the proper front
end changes). The tuning scheme currently centers BFO in the 2nd
IF passband for symmetrical SSB; I may add USB/LSB offsets.

7. RF section is fully enclosed in a tin faraday shield with a number
of bypassing schemes; some birdies are still introduced on the digital
I/O lines entering this can which I hope to squelch with properly
designed LPF.

8. Digital section is also fully enclosed in a tin shield and physically
separated from the RF section. I designed it around the Intel 8096
mcu; debugging and programming is facilitated by having an HMI-200 ICE.
Operating software is uploaded over an RS-232 port which also serves
as the control port for the receiver. The mcu has enough resources
to implement features such as ALE, digital modes, spectrum
surveillance,
etc. but DSP features will be offloaded to dedicated processors.

9. Audio monitor output is 8 ohm with provisions for stereo and a 5000 ohm
output feeds the audio stream server.

10. Receiver and antenna are viewed as an integrated system; the antenna
is a modified Marconi matched with a 9:1 impedance ratio quadrifilar-
wound balun, isolated primary, to a 50 ohm coax feedline. The antenna
has a good ground which has a very short lead to the balun ground
in the Marconi configuration. The feedline shield is not grounded but
is continuous to the receiver chassis which currently is also not
grounded (this is very low noise). The feedline is enclosed in
plastic pipe and buried 18 inches deep in the soil from the antenna
feed to the shack further attenuating noise. The system performs
well in a very hostile RFI/EMI environment; our QTH is noted for
some of the worst QRN anywhere and the huge antenna farm for
broadcasters
and public services is on a peak very nearby and causes much grief
for radios with less than excellent dynamic range/IMD and selectivity.

So far no one has tuned the receiver or made an audio connection. It is
remarkably easy to hear the audio using a SIP user agent (any voip phone
that permits dialing SIP URIs such as '. I had
suggested 'firefly' which is what I use, but it only handles numeric URIs
(so it must be registered on the callee's SIP proxy server). Instead I
recommend a version of X-Lite, which I made available at:

ftp://ftp.cybertheque.org/pub/xten

This is a Windows SIP softphone which permits dialing our SIP uri from
another network, .e.g. iptel.org. Please set up a free account at
iptel.org,
download and install X-lite, configure it for the iptel.org account, and
dial the above URI to hear the audio. Access the web page to control the
receiver. At some point I hope to dispense with the need for SIP dialing
by including an RTP audio player applet in the web page (such a beast
isn't currently available, only JMF heavyweight code which is unsuitable).

Regards,

Michael

"msg" wrote in message
...

W3JDR wrote:
Very well thought out, and a fine piece of homebrewing.

The suggestion about writing a QEX article is right on. I'd sure like to
learn more.

Keep us informed


Thanks for your encouraging words; I hope to write an article
and do intend to publish more data on the project.

Regards,

Michael

msg wrote:

Homebrew online HF receiver located at approx. lat. 46.8,
lon. -92.1 is now accessible at:

http://www.cybertheque.org/homebrew/rcvr


I would like to clarify how my online interface is
different from the 'web controlled receiver' RCSweb
(N30EA) interface commonly used for Internet access,
which may make it worthwhile to take the time to
configure a SIP client to hear the audio. The
RCSweb interface posts commands from web forms to
the radio to make settings; the user fills out a
form and waits for the results to appear at the
receiver, often the user must 'reload' the web page
to see if his settings were honored. Most often
the audio is streamed using mp3 encoding and
suffers from buffering delays of many (up to 30)
seconds as well as network QoS latencies. There is
no provision for hands-on tuning as you would do
if you were physically at the receiver.

My interface provides an interactive hands-on receiver
tuning and controlling session; there are no forms to
fill out, no page refreshes required and no waiting or
latencies for settings to take effect. The audio is
streamed in real time so that you immediately hear
the results of your control of the receiver.

My thanks to those who will try this and provide some
feedback of their experiences.

Regards,

Michael

You should consider contributing an article
to QEX.

Pete k1zjh

Uncle Peter wrote:
You should consider contributing an article
to QEX.

Pete k1zjh



Thanks, I'm working on it.

Regards,

Michael