PropNET: Frequently Asked Questions

Note: This is a dynamic document subject to updates and change over time.

General Introduction

The Project, the Program and the Particulars

Playing on PropNET - Playing by the Rules

Playing on PropNET - Playing nice with others

PropNET is the name given to an innovative project that uses PSK31 to create an RF-based digital peer-to-peer network. Participants simply download PropNetPSK (a Windows program), enter a few station-specific parameters in order to take part.

Most PropNET participants automatically identify themselves over-the-air, typically a few times an hour and pass traffic to other participants. If a receiving PropNET station “catches” (decodes) the transmission, the details are logged locally and the event is plotted on a local map. If the receiving station is connected to the Internet, the “catch” is also reported to a globally accessible website (http://www.PropNET.org). The process repeats over time, resulting in a significant amount of network-exchanged information that can be used for many purposes, including the observation of ones own transmission quality (see the FAQ on IMD).

TOP

2. Why is the term “PropNET” copyrighted?

Though the PropNET Project is a federation of innovators and experimenters, coordination and quality maintenance is important. By requiring developers (and potential developers) to receive permission to use the term in their products, it is hoped that such coordination would become natural and a high degree of quality and functional compliance can be maintained. There is nothing more to it than that. TOP

3. On what frequencies is PropNET activity found?

The following frequencies are in MHz and refer to the transceiver frequencies, USB:

1.9982 3.5982 7.1032 10.1389 14.097 18.105 21.098 24.924 28.131 50.291 144.288 432.300

Participants are encouraged to anchor on one of the frequencies in bold rather than spreading out across multiple bands. The PropNET concept works best with long-term and constant participation on a a particular band. Activity engenders additional activity.

Please note the 160 meter frequency that is underlined above. The 160 meter band has no USA allocation for Automatically Controlled Digital Station operation. If operating there, a control operator must be present at all times.

These frequencies are called “Anchor frequencies”. They are the frequencies to which one tunes their transceiver (USB). The PSK31 stream occurs above that, in accordance with a participants continental assignment.

For example, for the 30m band, the table shows that you need to set the radio to 10.1389MHz USB. Then, if you live in North America, you configure PropNetPSK to use a PSK31 stream frequency of 1500Hz. The on-air transmit frequency will then be the sum of these two frequencies; i.e. 10.1389 + 0.001500 = 10.1404MHz.

Note that although you set the radio to a frequency just below 10.140MHz, the on-air signal actually appears just above 10.140MHz. This means that the signal falls inside the United States allocation for automatically controlled digital stations (10.140-10.150MHz) and is therefore legal. TOP

4. Can a PropNET network be implemented on non-Amateur radio frequencies?

YES, provided such operation is permitted in that service, of course! In fact, we're hoping that someone involved in the experimental activity on the 500 kHz band will activate as a transmitting station. Doing so could engage a large number of non-licensed participants in the form of receive-only “lurkers” who could automatically web-report receptions of their experimental transmissions. TOP

5. How does PropNET settle upon its operating frequencies?

Participants in the PropNET project apply the “good amateur practice” of researching spectrum segments that permit automatically controlled digital operations, then they spend a considerable amount of time listening and scanning for other regular on-air operation by others in those segments. Using 30 meters as an example, in addition to these strategies, the PropNET community ran a study of “DX Cluster spots” to identify the segments of the band that are least used for “DX chasing”. The result of that study is that the PropNET Anchor frequency moved into a less-used segment!

Because PropNET uses PSK31 as its mode of operation, we attempt to find spectrum at the edge of existing PSK31 operation if possible.

When a “best possible” segment is identified, a pilot contingent of PropNETers will establish operation and await the outcome. Since the preamble includes web site information and the payload includes the call signs of the PropNET participants in plain text, PropNETers are easily reached should their operation be problematic in any way.

With the absence of insurmountable negative feedback, an “anchor” frequency is established and communicated. TOP

6. How do I find out more about PropNET?

The quickest way to discover how PropNET works is to try it! Download the PropNETPSK client, follow the very informative Help file included with the client, and you’re there.

You might also subscribe to the PropNET-Online Yahoo group (http://groups.yahoo.com/group/PropNET-Online). There you will find all kinds of active discussions and helpful advice on how to use PropNET.

If you have any special feedback or suggestions on how to improve PropNET, send an e-mail to PropNET-Online-Owner@yahoogroups.com

TOP

7. What is the difference between PropNET and PropNetPSK?

PropNET is the name of the “project” - the network formed by participants.

PropNetPSK (also known as PNP) is the name of the Windows-based client that is used by PropNET participants. It can be downloaded from this web site. TOP

8. What are some of the key features of a PropNET software client?

Key features of PropNET "sanctioned" software focus on the ability to make contol-operator like decisions and to support (and be sensitive to others') on-air communication in one way or another. It is with particular pride that we can say that it includes an anti-QRM feature that is a new concept to the digital world: “listen before ID”. This strategy makes it impossible for PropNET participants to interfere with other transmissions on the frequency (provided they can be heard by the PropNETer, of course).

Another function of interest is that of scanning for other stations that may be calling them. If a return call is decoded, a PropNET client should be able to invoke a “QSO Alert” that will alert the operator that someone just called them. The PropNET station can then engage in a keyboard QSO, if they're so inclined.

If connected to the Internet, participants stations will directly report their activity to a central data collection hub for casual observation by “anyone in the Internet universe”! TOP

9. PropNET transmissions appear strange. What does it all mean?

A PropNET transmission is a PSK31-encoded character string, and includes two components: the preamble and the payload. For example:

~~~~~~~~~~~~~~~~~~~~~~~~~~~

FOR INFO: http://www.PropNET.org < Preamble

ab4yz>hy:[fm19oo]PHG211066/^D644 < Payload

~~~~~~~~~~~~~~~~~~~~~~~~~~~

The preamble exists to give decoding software time to scan and lock on to the PSK31 stream.

The payload includes much of the same information that voice or CW operators exchange in a typical contact, but in a shortened form to minimize on-air frequency use. It consists of:

• the callsign of the transmitting station (“ab4yz” in the example);

• a two-letter band code (“hy”, which refers to 10 meters);

• the station’s location, expressed as its 6-character Maidenhead locator (“fm19oo”);

• the station’s Power/Height/Antenna Gain (PHG) code (“211066”);

• a checksum of the payload (the four characters after “^”).

The payload is relayed by receiving stations to the server at www.PropNET.org where much of the payload is automatically decoded and displayed.

There is also an online calculator into which anyone may plug-in a received PHG: http://www.pearhead.org/PropNET_PHGRA_decoder

TOP

10. Would you explain the two-letter band codes?

Every frequency band from 30kHz through 300GHz has been assigned a two-letter designation by the PropNET Project. Those that correspond to experimental and amateur frequency allocations are as follows:

TOP

11. What is encoded in the PHG value?

Keyboard PSK31 operators will often exchange information about their stations. Exchanges are often encoded in repetitive “brag files” that include their location, power output, antenna type, etc. PropNET operation encodes much of this same information in the payload, some of it is in the PHG.

APRS users will recognize the PHG code concept. In PropNET, however, the code has been expanded to include the number of ID transmissions per hour.

PropNET PHG code is actually a PHGDRA/ code (appearing, in order: Power,Height,Gain,Directivity,Rate,Altitude).  The encoding of this information allows PropNET network participants to exchange station-information quickly and efficiently.  The encoding table is shown below:

In a typical PSK31 contact, an operator may pack their brag file with information that looks like this: "I am running 25 watts to a 4 element beam at 40 feet here in the high desert of Arizona"  A PropNET participant's station can convey the same information by exchanging "PHG526649" along with a 6-character Maidenhead Grid locator.

Notes:

1: Square root of the TX power.

2: Log2 (H/10), where H is the antenna height above the local average terrain.

3: Antenna gain dBi. If more than 9dBi, use A=10, B=11, C=12 etc.

4: Azimuth of main antenna lobe.

5: Transmissions per hour. If more than 9 per hour, use A=10, B=11, C=12 etc.

6: Log2(h/10), where h is the height of the antenna above sea level.

To "manually" decode the PropNET PHG code, enter it in the webform here: http://www.pearhead.org/PropNET_PHGRA_decoder

TOP

12. How often do PropNET participants ID themselves?

On HF frequencies, it is recommended that participants ID no more than six times per hour; however ID rates of up to 15 times per hour are allowed. The station owner is responsible for setting this parameter to a reasonable value. TOP

13. Are IDs timeslotted?

No timeslotting takes place by design. Each participant is stand-alone and autonomous in its operation. Normal differences in computer clock time and time keeping will cause participants to wander into and out of “sync” with others over time. This is a good thing as it offers some natural randomization. TOP

14. I am unlicensed. Is there some way for me to add to the value of the PropNET project?

Yes! Download the software client, tune your shortwave receiver to an “anchor” frequency and operate as a “lurker” (an RX-only participant). If your computer is Internet-attached, you will even appear on the Internet map. Any station you decode will show up there too, with a vector connecting the two of you. You will be identified on the map by your 6-character Maidenhead grid square when you are a lurker. TOP

15. Why are some symbols on the Internet maps on PropNET.org shown as “L” or by their Maidenhead grid square?

This indicates that the participant is a receive-only “lurker”. In other words, don't be concerned if you never “catch” (receive) a station on the air that is labelled that way, because they aren't transmitting! TOP

16. What rules govern the PropNET service?

PropNET is considered an international service. However, radio licensing regulations differ from country to country, so it is important for PropNET participants to know and abide by the rules of their own licensing authority.

17. What rules govern the PropNET service in the United States of America?

Radio amateurs in the United States are bound by the requirements of the FCC Part 97 rules. (www.fcc.gov/Bureaus/Engineering_Technology/ Documents/cfr/1998/47cfr97.pdf). The PropNET network was designed with the rules governing Automatically Controlled Digital Stations in mind. Of course, the operator will start PropNetPSK manually, but thereafter it is under automatic control, and the Part 97 rules that are specifically applicable to PropNET include the following (the § numbers refer to Part 97 paragraph numbers):

Automatic Control

1. §97.3(6) defines “automatic control” as “The use of devices for control of a station when it is transmitting so that compliance with the FCC rules is achieved without the control operator being present at a control point.” (italics added)

2. §97.221(b) says that “A station may be automatically controlled while transmitting a RTTY or data emission on the 6m or shorter wavelength bands, and on [the following] segments.”

28.120 – 28.189 MHz	14.1005 – 14.112 MHz
24.925 – 24.930 MHz	10.140 – 10.150 MHz
21.090 – 21.100 MHz	7.100 – 7.105 MHz
18.105 – 18.110 MHz	3.620 – 3.635 MHz
14.0950 – 14.0995 MHz

It is important to remember that even with the strategies that the PropNetPSK program has invoked to allow for automatic control compliance, it is the station licensee that is ultimately responsible for their station's proper operation.

In summary, this means that you can operate PropNET on the 6m or shorter wavelength bands, and on the automatically controlled sub-bands from 10m to 80m listed above, without being present at your station, while still being ultimately responsible for your station's proper operation.

Interestingly, PropNET operation may take place on any frequency upon which digital communication is allowed (even outside of the Automatically Controlled Digital Station sub-bands), provided the station operator is in either direct (a) local or (b) remote control of their station. PropNET operation on the 160 meter band is a good example. TOP

18. My country (or personal operating style) doesn't allow me to operate as an Automatically Controlled Digital Station. What options do I have?

That's easy. Consider transmitting only when you are present at your station. When you are not, stay active but enter “Lurker” mode. That will make you receive-only, yet your station will still report anything that it “catches” to the Internet hub (if you are Internet connected, of course). TOP

19. I don't see PropNET stations communicating with other stations. This seems more like a “beacon” than it does a “network”, doesn't it?

PropNET stations communicate with other PropNET stations using unconnected datagrams. This is similar to APRS' UI-frame packets and UDP in the computer world. Communication is taking place between PropNET stations even though it is unacknowledged (no ACK's).

As a further differentiation from “beacon operation, non PropNETers can attempt to “break in” to the network by transmitting a PropNETer's callsign a few times on its transmit frequency. This could invoke a “QSO Alert” that signals the operator. It could potentially start a keyboard QSO. Of course, the operator may choose to ignore your “break”, in which case you could QSY to a clear frequency to call CQ yourself, secure in the knowledge that the band is indeed open for communication. TOP

20. If PropNET is used to study propagation, it conforms to a definition of a beacon, doesn't it?

The core-purpose of the PropNET project is to advance the state of the art in the Automatically Controlled Digital Services arena.  One of the greatest unknowns is how to automate the actions of a control operator, if they were present.  Even the FCC is silent on that point.  PropNET is pioneering in this way (and getting better at it over time).

Can PropNET be used to study propagation?  Of course!  Many services are used to study propagation. These include broadcast TV and radio and the APRS network (See: http://mountainlake.k12.mn.us/ham/aprs/path.cgi?map=na).

PropNET was designed to operate in accordance with the rules found in the US's  47 CFR Part 97.221(b) in focus.  While a PropNET station certainly includes components that can support the study of propagation, so do traditional PSK31 QSO's.  PSK31 QSO's involve the exchange of information, and are often "spotted" to DX clusters.  PropNET operation involves exchanging this same information and spots its presence and partial and fully-successful exchanges it's own Internet based web site, automatically.   TOP

21. How does PropNET fit in with other band users?

Proudly, PropNET was designed to be a non-exclusive, frequency sharing friendly, band co-user. A significant amount of strategic effort has been expended to ensure that the PropNET Project participants stations automatically observe “good amateur practice” in their operation.

In order to be PropNET sanctioned, a PropNET software system must display a degree of on-air awareness. This means that it must modify its behaviour in the presence of other signals, in a similar way that a human control operator might if faced with similar knowledge. In the absence of specific guidelines to the contrary, PropNET project leadership has insisted that client software must be capable of applying good amateur practice, to the extent that this can be defined and programmed. TOP

22. How does PropNetPSK automatically apply “Good Amateur Practice”?

According to the FCC (as quoted by the ARRL), "Good amateur practice is a hard thing to define. It's operating with the realization that frequencies are shared, that there's going to be occasional interference and that's no reason to become hateful and paranoid." With this in mind, the PropNET client software (PropNetPSK) includes a component that assures that the transmitting frequency is clear before a transmission takes place.

There are two layers of transmit-control strategy presented. Within the PropNetPSK client, there is a transmit watchdog timer that will force a transmission to cease after 60 seconds.

Additionally, PropNET participants are strongly encouraged to employ hardware time out timers if their transceivers have them.

PropNetPSK will listen before transmitting and hold-off transmitting until it perceives the frequency is not in use.

Of course, there is always room for improvement. Participants are encouraged to suggest new ways in which good amateur practice can be applied. Innovation and evolution are the cornerstones of the PropNET project. TOP

23. I have noticed a PropNET station interfering with another station on the HF bands. How is that considered applying good amateur practice?

The “listen before transmitting” function is a core tenet of the PropNET project. PropNET client software, such as PropNetPSK, can not transmit if it perceives that its TX frequency is in use by other signals. Conversely, if it doesn't perceive the frequency being in use, it will certainly transmit. This can occur for many reasons, including:

• it doesn't hear the other station, even though you (as a distant observer) can

• one-way propagation;

• high noise level at the PropNET station's location;

Those familiar with HF propagation must realize that they may be faced with a situation where they hear both a PropNET station and a conventional station at the same time, yet the PropNET and conventional station can not hear each other.

Download the client and participate for a time. If you can uncover the circumstances under which it transmits when the frequency is in use, please tell us. We can fix it, and you can be part of the evolution of the system. TOP

24. What PropNET strategies assure that split-frequency DX operations are not interfered with?

It should be noted that split-frequency operators are likewise required to assure that their transmission isn't interfering with other band occupants. They are equally obligated to apply “good amateur practice”.

If a “split operating” DX station is transmitting on a frequency that is likewise occupied by a PropNET station and the PropNET station can hear the DX station, the PropNET station will not transmit. Of course, once the DX station ceases transmitting and begins listening “up 2kHz” for replies, the PropNET station will then transmit, as it perceives the frequency to be vacant (which it technically is).

Rhetorically, how long should a PropNET station hold-off transmitting? A similar question could be asked of an SSB station when, during contests one often hears a station ask, “Is the frequency in use?” and half a second later begins calling “CQ”. :)

Improvement is a continuous process. Please offer strategies to consider as the PropNET founders attempt to evolve the system’s “automated awareness”. TOP

Updated:

27 February 2008

8 March 2008 revision

14 March 2008 revision

19 March 2008 revision