LP-PAN
From Zerobeat
June 14 2008 - LP-PAN is being shipped, the final shipments from the first order group are expected to be made during the week of June 16, 2008. The second order group is nearly sold out. LP-PAN accepts the IF output from K3 via the accessory KXV3 transverter interface and presents this to a computer sound card input. From there, multiple applications can display and analyze the sample. At the present time LP-PAN is in preliminary stages. The Creative Labs E-MU 0202 external USB 2.0 audio interface is presently the preferred (tested) device. OS previous to Windows Vista is also likely to be the most compatible at this early stage.
- LP-PAN Quick Start - notes from a successful installation.
Shipping schedule
June 19 2008
All LP-PANs from the 1st run have been shipped. I have only a few left to sell from the 2nd run, and have already ordered parts for the third run. I am still running a few weeks behind orders for shipping, but I'm closing the gap ;-) Scott has sent me an alpha of IF Stage v0.92, and I plan to post an LP-Bridge beta this weekend.
Larry N8LP
LP-PAN Recommended items
- LP-PAN kit ($175) or assembled ($225) from www.telepostinc.com
- Creative Labs E-MU 0202 USB external audio interface for 192 kHz display (~$100)
- M-Audio Audiophile 2496 PCI for 96 kHz display (~$100)
- Radio Shack 42-2433 shielded audio cable 1/4 to 1/8 mono. 2 required for E-MU
- Radio Shack 42-2444 shielded audio cable RCA to 1/8 mono. 2 required for M-Audio
- Radio Shack 278-964 BNC Coaxial Cable 50 ohm male BNC ends
- Windows 2000, XP, Vista computer. No 2000 driver for E-MU.
Frequently asked questions
1. What is LP-PAN?
A direct conversion receiver with quadrature detector to provide I and Q audio signals for connection to a sound card. It is designed to receive a range of frequencies centered on 8.215 MHz, the IF frequency of the K3. By using quadrature detection, a total bandwidth equal to the sampling rate is obtained, ie. 192 kHz sampling will give almost +/- 96 kHz tuning range, etc.
2. Does LP-PAN require a PC?
Yes. A PC and sound card are required to use LP-PAN. Suggested PC configurations are given above in the General Information section. They are similar to what would be required with any SDR type radio application. The software application does the IQ decoding and provides a spectrum display, second receiver, etc.. Other applications, like CW Skimmer provide other functionality. See Software section above.
3. Will LP-PAN work with a Mac or Linux?
LP-PAN depends on the use of an SDR application. There are a number of these around. The most popular is probably PowerSDR from FlexRadio, which is an open source application, but a quick search doesn't reveal a version for Mac. I don't know what options there are for a CAT interface / logging program using platforms other than Windows. I plan my own dedicated application with specific K3 oriented features, but it will only be for Windows. You might consider Wine or Parallels or VMware, or using a dual boot configuration. Make sure your sound card is supported though, especially if it's Firewire based.
4. How does LP-PAN interface to the K3?
It connects to the IF output. You will need the KXV3 option for the K3. The K3 also needs to connect to a PC serial port to provide frequency data to the SDR application if you want the display to show actual tuned frequency. LP-Bridge will allow interfacing the K3 to LP-PAN and several other programs at the same time for full bi-directional serial control from all applications, without adverse interactions, and with very easy configuration in one simple program.
5. Can LP-PAN be used without a serial interface?
Yes. The program can be set up to display relative frequency referenced to an arbitrary center frequency, like 0kHz or 8.215 MHz. To use point and click tuning, or to display actual receive frequency, a serial port connection is required.
6. What software is required for point-and-click tuning with the K3?
This is currently available using the PowerSDR-IF Stage sub-version that Scott WU2X has written along with HRD (see discussion earlier on this web page in the Software section). There is still an issue about offsets. K3s with 5 pole filters use an offset to adjust for filter variations. In other words, the IF is not exactly at 8.215 MHz with those filters. Wayne at Elecraft has indicated that he will make the offset data available through a serial port command. This will also come in handy to keep PowerSDR centered as the IF shift and Hi/Lo Cut controls are adjusted. The offset information is needed because the K3 LO is offset when adjusting these controls, and results in the passband at the IF output port being shifted slightly. LP-Bridge will provide an extensive link to Scott's PowerSDR-IF Stage program, and simultaneously allow bidirectional communications with several other programs at the same time.
7. Will LP-PAN be sold as a kit or as an assembled unit?
LP-PANis available both as a partial kit (with pre-installed SMD parts) or fully assembled unit. Kit builders will need to adjust the input bandpass filter, but I have designed the filters to allow this to be easily done. The resulting adjustment should provide a passband flatness of about 1dB. If the builder wants it better than that, he can send the unit to the factory (with pre-paid return shipping) for the adjustment. This takes only a couple minutes to do using my HP VNA. I haven't seen any obvious advantage to factory tuning, but it could affect image rejection slightly I suppose.
8. What is required to connect LP-PAN to my K3 and PC?
A 50 ohm coax cable with BNC connectors to connect LP-PAN to the K3 IF output. For audio, a pair of balanced or unbalanced cables with 1/8" mono/stereo phone plugs on the LP-PAN end, and appropriate connector(s) / adapters on the sound card end is required, depending on the sound card. Also, a source of 11-16VDC @ 40mA. LP-PAN is supplied with a power cord with 2.5mm DC connector on one end and tinned leads on the other. It can easily be powered by the accessory 12VDC output of the K3. An RCA "PTT" type jack is provided for muting PowerSDR during transmit. This is only needed if you find that the software muting provided by LP-Bridge isn't fast enough for the modes you use. The Mute input requires a short to ground to mute, and no more than ~ 7VDC when not muted. For safety, an isolated relay or open source transistor driver is recommended.
9. What features does LP-PAN offer besides a spectrum display?
Spectrum/panadapter display is only one feature that can be used with LP-PAN. Features are application dependent, and vary from program to program. I have played mostly with Rocky and WU2X's IF version of PowerSDR so far. In addition to the panadapter display, I have used LP-PAN as a second receiver for SWL'ing. PowerSDR has a nifty synchronous AM detector that makes SW listening a pleasure. It can also decode digital voice modes and a host of other things. As a receiver, it performs very well. See the performance section above. I have also played a bit with VE3NEA's very clever CW Skimmer program, which allows you to see dozens of decoded CW signals at a time for a section of the band, and it displays callsigns and RST reports for all the stations, plus a decoded message section for the signal you are listening to.
10. Can LP-PAN share a sound card with other applications?
This can be done with the low cost VAC (Virtual Audio Cable) program, but there are a couple problems with this approach. One has to do with resampling of the audio signal and resultant artifacts. Another is that you may want to feed the K3's audio to the other applications instead of LP-PAN's audio. I recommend a dedicated new card for LP-PAN to get maximum bandwidth, resolution and overall performance. The card I am using is an external USB sound card, and easy to add to any system. An inexpensive (probably built-in) sound card would suffice for the secondary sound card. I have also done some preliminary testing of the sound card built into the microHam MicroKeyer II, and it seems to coexist with the LP-PAN's sound card without problems. Some applications can share the sound card without any special programs, as long as PowerSDR and the 2nd program are set to the same sample rate, and the WDM driver is used for both. There may be other ways to do this as well, but I have done this one successfully.
11. What sound cards give the best performance?
I have only found one good 192kHz card at reasonable cost, and in fact there are damn few at any cost. This is the Creative Labs E-MU 0202 external USB sound card. It also provides 24-bit depth. All other cards I saw that claimed to be 192 kHz had problems, or only used that sampling rate for output (playing music, etc.) LP-PAN requires a card that also can "record" at 192 kHz. The E-MU card lists for $150, but I paid about 60% of that price for mine, plus shipping. If you can be happy with a 90 kHz wide display, there are some good 24-bit/96kHz cards around. The M-Audio Audiophile 2496 PCI card works extremely well, and the professional Delta44 is good with one caveat. See the Sound Card Info page for more details. For Firewire interfaces, I have found two acceptable cards. The M-Audio Firewire Audiophile is excellent up to 96 kHz, and the Edirol FA-66 works well up to 192 kHz sampling, but usable display bandwidth is about 150 kHz. There is another caveat as well, and you can read about it on the Sound Card Info page as well.
12. Do I need to be a computer expert to get this all working?
No, but you need to be comfortable with installing Windows software. There are three things you will need to install. PowerSDR-IF Stage, sound card drivers and either LP-Bridge or Ham Radio Deluxe. PowerSDR-IF Stage is the program that displays the panadapter and allows basic K3 frequency and mode control. The sound card drivers will come on a CD with your sound card, or can be downloaded from the manufacturer's website if you want the latest versions. Ham Radio Deluxe or LP-Bridge are required to connect to the K3 and provide the linking to PowerSDR-IF Stage. There are links at the top of this page to these programs.
