Focus on Competition
A Note From the Technical Director
Bob Underwood
As the year bumps to a close, many clubs and individuals will reflect on how the frequency "wars" progressed. Just as 1984 became a target date for conversations on the state of mankind after the writings of Orwell, 1991 became a focal point for modelers regarding radio concerns. While the "magic" date was nothing more than a hoped-for goal for the ending of the phasing in of the new frequencies assigned to us in 1982 by the FCC, everyone seemed determined to attach meanings that ranged from Orwellian-style phrases like "It's the end of the world," to legalistic terms for what could or could not be used any longer.
All during the year some clubs have grappled with member tugging concerning frequency matters. For some, it's been divisive. Other clubs have weathered the storm in great shape. One group that appears to represent the latter is the Northern Virginia Radio Control Club (NVRC), presently with over 300 members and growing. They elected to approach the frequency usage matter "cold turkey" at the beginning of 1991 and institute the use of all 50 of the 72 MHz frequencies. They required narrow-band transmitters and receivers.
It should not be inferred that they slipped into this scenario without debate, for indeed some members did not wish to embrace this approach. However, the group enjoys excellent leadership and operates democratically. The majority prevailed. Is the system working for them? Consider the following report generated by Bill Hershberger, a member of the club:
NVRC Monitor Report Summary (by Bill Hershberger)
The Northern Virginia Radio Control Club has a total membership of over 300. In late 1990, after lengthy discussions, the members voted to use all of the 72–73 MHz channels effective January 1, 1991.
In order to provide safe and proper channel use, it was decided that all equipment (transmitter and receiver) must be narrow band. The membership decided that the only RC equipment that would be allowed to operate at Arcola, Virginia, must be of a type that is certified to be narrow band by a registered professional test laboratory and is listed in Model Aviation.
It was also decided, on a progressive basis, that channels 20 and 21 would not be used at Arcola because of the signal level from TV-4. The plan was to observe and evaluate the effects that the TV-4 signal might have on the new narrow-band equipment before those channels were opened for regular use.
Club members expended considerable efforts to assure proper phase-in of the new channels and the use of compatible narrow-band equipment. A new frequency control board complete with frequency pins was designed, constructed, and installed at Arcola in order to accommodate the use and control of all new channels.
Use of the new odd-numbered channels, with the exception of 21, increased on a gradual basis. Following the winter months when flying weather improved, it became apparent that the increased activity on the flight line and pit area required additional coordination through the monitoring of the frequencies in use.
Starting in May 1991, the ICOM-7000 and the Aero-Spectra channel analyzers were taken to Arcola for monitoring the RC bands. The attached Monitor Report for June and July 1991 provides information on field activities and use of the new channels. An analysis of this report reveals some interesting data:
- The 20 kHz-spaced channels are providing reliable service. Simultaneous operation on adjacent channels produced no known cases of interference. Equipment in use during these periods included the most expensive to the least expensive RC units listed in Model Aviation.
- Dual- and single-conversion receivers were noted to be in use during simultaneous adjacent-channel flights. No instances of interference were noted.
- No "glitches" were experienced from commercial stations that were active adjacent to the RC channels. It appears that an adjacent commercial station must produce a signal level of at least S-9 on the ICOM-7000 receiver before "glitches" or interference are noted on a narrow-band receiver.
- It is anticipated that the remaining odd-numbered channels will be occupied as 1991 draws to a close. Based on experience to date, serious interference problems should not occur when all channels are observed to be operational in the 72–73 MHz band at Arcola.
- The number of frequencies in use at one time on the flight line cannot exceed five, which is the limit of planes allowed in the air simultaneously. The greater number of channels now available has a tendency to increase the number of RC channels in use in the pit area for testing and adjustment. On occasion the pit frequencies totaled six. No instances of interference were noted.
Use of precise and sensitive monitoring equipment, including the Aero-Spectra channel analyzer, provided a means for making an immediate determination about possible outside or internal interference to an active RC channel. The ability to directly access band frequencies without delays is a key element in an evaluation of potential interference.
A correct analysis has a direct bearing on the successful use of all RC channels in the 72–73 MHz band. For instance, it was necessary on several occasions to evaluate what was initially perceived to be interference when, in fact, it was discovered that there was low receiver or transmitter battery voltage, use of improper flight techniques, or a stalled condition which generated a no-control situation.
The monitor report reflects the total results of observing 14 days of flight-line operations in June/July 1991, including NVRC club contests, new equipment check-out at the field, equipment distance checks, and 23-channel separation checks for single-conversion receivers.
The 72–73 MHz band observations were made during the busy Saturday–Sunday flight operations plus periods during the week when operations were at a minimum level. Should use of RC channels change at Arcola in a way that is less successful than described in this report, details will be supplied in a manner similar to the format of this report.
Bill didn't editorialize very much; however, I can attest to the fact that he is pleased with the success enjoyed by the club. One reason is that Bill, as a member of the Frequency Committee, sees the outcome as proof that the system works.
Since I also fly at the NVRC site as a member of the club, I know he shares the great feeling that occurs when you go out to the field to fly, knowing there are no radio hassles; no mind-bending discipline needed for IMs and the like. All a body needs to do is to see if a flight station is open, see if your frequency is clear, take the pin and fly! It's just like the old days! Bill's monitor report is not included here but contains information listing pager activity with field-strength readings, observations of adjacent-channel operations, and the total number of channels being used at Arcola. Interestingly, the last item indicated that 20 even channels and 13 odd channels were being used.
Other happenings have proven the same point. In several reports following the CLRC Nationals this year you may have read about what happened at Soaring. On one of the days of competition, the officials went through the transmitter impound and found forty-seven different frequencies (including a few 6 meters) represented. A sample of each box was selected, and the transmitter and model for each were taken out on the field.
Everything was turned on and the question was asked, "Any problems?" There weren't any! Later in the day someone noted twenty-plus sailplanes, all in tow, in the same thermal. It's important to consider that there were also twenty-six modelers with transmitters scattered all over the site as well. Any problems? There weren't any!
Does the system work? Can all 50 frequencies co-exist in a safe manner? It certainly looks that way.
It should also be noted that there are clubs operating quite nicely with the alternate -1 and -2 plans that can be found in the Membership Manual. For the most part those clubs fly in rather remote areas where commercial operations are not a problem for the older wideband receivers. The clubs using only the even-numbered channels are the ones that have often had internal problems. Gradually, for whatever reason, odd-channel-numbered equipment begins to show up. Those clubs using the alternate-2 plan begin to find people wanting to use odd channels on the upper end of the band. At that time debate begins to develop.
Focus on Competition
In an effort to accommodate those people, the club will modify their plan by allowing the use of the odd channels but requiring that individuals with older equipment take extra pains to prevent intermodulation or adjacent-channel interference. Sometimes this just further fuels the "frequency wars" because of the added discipline required and the fact that one person will tie up four (or so) frequencies every time he flies.
In the final analysis, these club debates produce an interesting scenario at the headquarters end of the phone or mail. Two years or so ago, when the members perceived they were going to have to throw away old equipment, we were besieged with communications beseeching us not to pursue that course of action. Now the calls and letters ask us to do something that will require their club to go narrow band!
Sorry! It's up to your club to determine your needs and develop the program.
To end this column perhaps we should say that it's a little like the old phrase, "Catch-22." In this case, perhaps we should say "Catch 23" since it's the odd number that does us in!
Until next month!
Transcribed from original scans by AI. Minor OCR errors may remain.
