70cm ATV History and case for modified future HSMM use - Notes and Misc.

First, here is a recent example of how the rules change as we do, from March 2011:




The petition asks the FCC to allow those amateurs who are presently using a Motorola narrowband (12.5 kHz) digital land mobile system -- commercially marketed as MotoTRBO -- to be used legally. Because of some restrictions in the Part 97 rules, the TDMA repeaters (which are multiple-time-slot devices) are legal, but the mobiles and portables are not because the emissions used ….

The KA9FLX repeater in Chicago, IL was the first Mototrbo Amateur Radio Repeater. It was put on the air in 2008. At the time of this petition, there are more that a dozen Mototro repeaters in service on amateur frequencies.  Since then, over 90 repeaters have been reported as up and running.

It appears that some overly concerned fellow Amateurs on the radioreference forums brought the this emission rule technicality to the forefront.

In early 2011 the issue was raised as to the legality of DMR/MOTOTRBO for use under FCC Part 97 . Motorola had classified MOTOTRBO as emission types 7K60FXD (data only mode) and 7K60FXE (data and voice mode) . A careful reading of Part 97.305 led many to conclude that these emission types are not allowed in the Amateur Radio Service

The ARRL petitioned the FCC to revise the rules to clarify the situation and allow DMR on the ham bands . In March 2011, the FCC opened RM-11625 and asked for public comments. While over a year later the FCC has not taken action . Motorola filed with the FCC to add new emissions designators to the MOTOTRBO equipment. The modes of interest to amateur radio are 7K60F7W for the repeater stations and 7K60FIW for the user radios. These emission types are specifically allowed in Part 97 .

Since there have been no public enforcement actions on the part of the FCC, we have to conclude that they don' t see a problem.

Open source advocate, Bruce Perens, K6BP who has been promoting the Codec 2 project, filed comments in December 2012, in reply to the TDMA debacle.  

To quote from his filing:

We urge FCC instead to apply a framework that recognizes the reality of communication today: one based solely on emitted bandwidth, rather than increasingly-blurry, and unnecessarily restrictive, definitions of emission “type.”

I am more concerned by underutilized spectrum, and red flags that people throw that deter experimentation in the hobby.

That said I have a few extra picture frames and would be fine framing my first "pink slip" over silly outdated rules in the name of experimentation.  As long as your “intent” is pure in amateur spirit, in my eyes this is the only major regulatory requirement you should concern yourself with initially.

I firmly believe that the rules will change as we do. The Part 97 Amateur Radio Service rules should not be inflexible with respect to the encouragement of new digital technologies which improve spectrum efficiency.

70 cm ATV History

In March 1949 Bob Melvin, W6VSV conducted possibly the first Amateur Television transmission in the San Fransiciso Bay area on 423 MHz.

In January 1974, the first 70 cm Amateur Television repeater, WR4AAG was allowed in the Washington DC area, by way of a FCC- STA to wave section 97.61(c). In March 1976, the FCC issued a public notice to waive section 97.61(c) for the period of one year to permit fast-scan ATV stations outside of the repeater sub-bands.

It appears that fast-scan ATV has been formally permitted on 70 cm since February 1959. (1)

Postwar Amateur Television

The repaid development and expansion of color TV receivers freed up lots of older black and white sets in the back rooms of TV service shops across the country and helped fuel the first boom in Amateur Television (ATV) activity on the part of Amateur Radio operators. Though the 1960s, most operation was done using monochrome equipment. Operation was confined to UHF frequencies and above (beginning what what is now the 420-450 MHz, 70 cm band), which meant that virtually all activity was local in nature and severely impacted by adverse terrain. (2)

While the short-term outlook for conventional ATV is bright, the long-term situation is quite different. Put bluntly, ATV operations based on NTSC (or PAL) broadcast standards have no real viability much past the end of the current decade! This may seem like a harsh assessment, but it is really a call to look seriously at what trends are viable in terms of future development and growth. Let’s start with the basis for the assessment itself and then look at where we should be going. The assessment is based on two issues:
- Equipment availability
- Spectrum management

Future Directions

Given the technological changes in broadcast television, there are only three possible trajectories for future development and they are far from being equal;
1. Do nothing and stay with the NTSC standard.
2. Adopt a broadcast DTV standard.
3. Develop Amateur Digital Standards.

Amateur radio is a communications, not an entertainment service. Given the changes sweeping the TV broadcast industry, this may well be an opportune time to break from broadcast standards with respect to ATV and craft a television option better suited to the needs and objectives of the Amateur Radio service. Properly conceived, such an effort can eliminate dependence on expensive DTV equipment, address the issue of responsible spectrum usage, and bring ATV closer to the amateur mainstream in terms of equipment requirements. If we suspend parochial perspectives and make the assumption that a full-motion television standard has a place in Amateur Radio, it is clear that the third option listed above has a great deal of potential. (4)

The subject of Digital Amateur Television made Stan, WA1LOU’s ARRL Surfin’ column a couple times in 2008.  As well as CQ-VHF magazine in 2004.

Despite this, there is still a surprisingly small amount of current D-ATV activities in the United States. (5)   Most DATV is in Europe, despite high costs. 

It has been said that Image communications were never intended to be a mode independent of phone.

With that said, I tend to agree with option three above.  

At the September 2012 DCC in Atlanta, GA, David Bern, W2LNX presented a paper titled "Experimenting with High Speed Wireless Networking in the 420 MHz Band."

His paper reports on testing two different manufactures of 802.11 mini-PCI cards capable of operation in the 70 cm ATV sub-band using 5 MHz bandwith.

Test applications were a Webcam video streaming program and a file download server program that ran on inexpensive netbook computers.

The test documented in his paper prove a sustainable data rate of  1 Mbit/s over 10 miles.

Packet / RTTY Data Rate History

I find it ironic that you can have a 6 MHz wide image transmission on the 70 cm band.  Yet at the same time there is a 56 kilobaud speed / 100 Khz bandwidth data rule for 70cm.

97.307(f)(6) States; “A RTTY, data or multiplexed emission using a specified digital code listed in 97.309(a) of this Part may be transmitted. The symbol rate must not exceed 56 kilobauds. A RTTY, data multiplexed emission using an unspecified digital code under the limitations listed in 97.309(b) of this Part may also be transmitted. The authorized bandwidth is 100 Khz.”

Section 97.307(f) of the FCC Rules limits the digital data emissions of amateur stations operating to maximum symbol rates.  In a digital system the symbol rate is the number of times per second that a change of state occurs. It should not be confused with data rate (also called bit rate) although in a binary system the values will be the same. The symbol rate limits date back to the Third Report and Order in FCC Docket 20777 and became effective on March 17, 1980, when amateurs in the United States were authorized to use ASCII. 

Please note that with modulation like OFDM, these limits pertain to individual carriers not the cumulative sum.  See: http://www.arrl.org/arrlletter?issue=2007-04-27

"In fact, 3 kHz bandwidth would have been a new limitation, because the present baud rate limit applies to individual carriers," he said. "Therefore, for emissions such as OFDM [orthogonal frequency-division multiplexing], which use multiple carriers, there is no effective bandwidth limit in the HF bands now." Sumner notes that under current rules, a single OFDM signal could conceivably -- and legally -- occupy an entire HF band."

It appears that the 56 kilobaud speed / 100 Khz bandwidth data rule for 70cm came into existence in the early 1980's when the FCC revised the rules to allow experimental digital codes and adopted ASCII as a standard. (6)

DVB-S used by some amateurs for Digital ATV has a signaling data rate that well exceeds this antiquated rule.  But that is classified as an image emission, which is exempted from the data emission rules.  Spread spectrum emissions are also exempted from the data emission rule.  While 802.11b uses direct sequence spread spectrum (exempt from the data rule), 802.11g uses OFDM, which is not classified as spread spectrum.

ATV Repeater Tally

ATV activity on the 70 cm band hasn't exactly been growing.  The following is graph of 70 cm ATV Repeaters (inputs, outputs or both on 70cm).  Data was taken from ARRL Repeater Directories for the years show.  It's hard to justify, of 20 MHz of space for exclusively for this mode.  I feel the gates should be opened to allow other possible co-existable wider band uses.

OFDM Can Be Classified as an Image Emission

John Stevensen, KD6OZH in 2005 began development of a HSMM Orthogonal Frequency Division Multiplexing (OFDM) Modem that will allow Radio Amateurs to have all –mode voice, text, data, and video (i.e., multimedia) high-speed digital communications on the VHF, UHF and SHF bands. Alpha testing of the OFDM modem was done in Texas using an ATV channel in the 70cm band operating in a digital “image mode” coined Amateur Digital Video (ADV).

In a January 2005 report to the ARRL board of directors, the HSMM Technology Task Force submitted the following concept as basis for such a 70 cm OFDM modem capable of Amateur Digital Video.

The 70 cm band is ideal for HSMM and, using the following interpretation of FCC regulations, we should be able to use OFDM modems with an occupied bandwidth up to 9 MHz (at least) on the 70 cm band. HSMM would be classified as an image emission type. This interpretation also allows 6 kHz (or more) bandwidth OFDM modems on the MF and HF amateur bands.

In 47 CFR 97.315 the emission type "image" is defined as including "emissions having B as the first symbol; 7, 8 or 9 as the second symbol; W as the third symbol".

In 47 CFR 2.201 (c) (2) a first symbol of B defines the type of modulation of the main carrier as an "emission in which the main carrier is amplitude-modulated (including cases where sub-carriers are angle-modulated) with independent sidebands". The OFDM modem fits this description as it has a central carrier with multiple subcarriers in the upper and lower sidebands that are angle (phase) modulated. In 47 CFR 2.201 (d) (5) a second symbol of 7 indicates that the nature of the signals modulating the main carrier are "two or more channels containing quantitized or digital information". 47 CFR 2.201 (d)(2) and (3) indicate that time-division multiplex is excluded for a single channel so the time division multiplex inherent in HSMM communications creates two or more channels. In 47 CFR 2.201 (e) (8) a third symbol of W indicates that the type of information to be transmitted is "a combination of the above" and that includes (4) "facsimile", (5) "data transmission, telemetry and telecommand", (6) "telephony" and (7) "television". HSMM fits this definition as it includes data, speech and image components.

In 47 CFR 97.305 "a station may transmit the following emission types on the frequencies indicated, as authorized to the control operator, subject to the standards specified in 97.307(f) of this part". The following table includes the "image" type for all bands and references 47 CFR 97.307 (f) (2) for the 160 m through 1.25 m bands but does not reference it for the 70 cm through 1 mm bands.

This is the only restriction on the image emission type and states that "the total bandwidth of an independent sideband emission (having B as the first symbol), or a multiplexed image and phone emission, shall not exceed that of a communications quality A3E emission". I can't find a definition for "communications quality" but it seems to be taken as 3 kHz on the MF and HF bands.

Thus OFDM modems using 6 kHz or less should be authorized on 225 MHz and below and OFDM modems with no bandwidth restriction on 420 MHz and above. If the emission must fit within the bandwidth used by existing analog image communication devices, that bandwidth would be 9 MHz for DSM AM ATV with a 4.5 MHz sound subcarrier.

[From http://www.ntms.org/802.11/ARRL Board of Directors 2005.doc ]

Why HSMM ?

Use it or Lose it

First and foremost it can put our microwave frequency allocations to good use.   These allocations (23cm-300GHz) make up 99% of hams total available frequency allocations. Yet, it's estimated that only 1% of hams are involved with any microwave operations.  

Of the above, over 99% of hams use a tiny fraction (0.3%) of the total ham frequency allocations while the remainder of our available ham allocation is essentially ignored. By the way, ARRL said that as of April 2010, there were about 688,500 personal ham radio licenses in the USA. If only one percent of these were microwave users, that would be 6885 hams. We often hear that the majority of licensed hams are inactive. How many microwave experimenters do you know?

About 40 years ago 2 meters and 70 cm were basically uncharted areas. Now they are populated. Undoubtedly the future of ham radio is in our huge - virtually unused microwave allocations. They have the necessary bandspace to support wideband modes capable of multi-media transport.

Nearest I can determine, the last time ARRL bandplans were reviewed was nearly 20 years ago for 50 MHz and above.

In April 2012 the FCC issued a public notice (Docket 12-91) titled "Commission Seeks Comment on Emergency Communications by Amateur Radio and Impediments to Amateur Radio Communications."  While a large part of this seems to focus on Covenants, Conditions and Restrictions (CC&R) rules and how they impact the amateurs ability, it does ask:

1 g. What communications capabilities, e.g., voice, video, or data, are available from Amateur Radio Service operators during emergencies and disasters? Are there any future technical innovations that might further improve the Amateur Radio Service?
2 d. Do any Commission rules create impediments to enhanced Amateur Radio Service communications?

The deadline for comment filing was May 17, 2012.   To look at what others had submitted, search for proceeding number 12-91. 

The FCC Uses & Capabilities of ARS Report to Congress was released August 20, 2012 (DA 12-1342).

Under "Other impediments"  (page 12) item 36 in the FCC report, they do acknowledge that:

36. Some commenters identified Commission rules that they believe impede advanced amateur communications. The ARRL asserts that the Commission’s regulation of emission types and digital bit rates is overly conservative and can prevent amateur operators from using the emission type and frequency suitable for transmission path and the information to be transmitted.

It's also worth mentioning that in some of the comments of Scot Stone Deputy Chief, Mobility Division of the FCC's in DA 08-1082 state:

We also believe that imposing a maximum bandwidth limitation on data emissions would result in a loss of flexibility to develop and improve technologies as licensees’ operating interests change, new technologies are incorporated, and frequency bands are reallocated. Additionally, we believe that amending the amateur service rules to limit the ability of amateur stations to experiment with various communications technologies or otherwise impeding their ability to advance the radio art would be inconsistent with the definition and purpose of the amateur service. Moreover, we do not believe that changing the rules to prohibit a communications technology currently in use is in the public interest.

There have been prior efforts to overhaul the bandwith rules.

Back in 1977, the FCC issued a NPRM, Docket 20777 suggesting a change from emissions authorization to bandwidth authorization.  And in November 2005, the ARRL formally asked the FCC to adopt the League's plan to segment the Amateur Radio bands solely by emission bandwidth rather than by mode (RM-11306).  In both cases, widespread misconceptions led to withdrawals of the proposals.

Powerful Transport Flexibility

High Speed Multi Media data links can support most of the traffic that the Internet currently does, including; remote printing and facsimile, video conferencing & instant messaging, voice, the Web (HTTP), file transfer (FTP), and forums.   D-Star Digital voice and data, Voice Over IP using SIP & Asterisk private branch exchange (PBX) open source telephony switching technology's well as Electronic Mail even via WinLink, AX.25 and more, can all be supported over a High Speed Multi Media network.  Talk about flexibility!

The concept is nothing new.  In 1989 Glenn, N6GN first described an inexpensive 2-Mbit/s microwave data link,  to build an amateur radio network capable of variety of applications, enabling amateurs to share resources. "Remote digital control of repeaters or even complete stations, including audio or video uplinks and downlinks, can be supported. Conventional voice repeaters (analog) may be replaced by digital hardware for completely digital round tables. Since this data can be transmitted anywhere the network permits..."  A decade later after the internet became mainstream, John, KE5FX detailed an Experimental Microwave Data Link for 10-Megabit Ethernet based on Glenn's work.  John, noted that "little progress has been made towards realizing the benefits of high-speed data networking in the Amateur Radio realm" and documented his work  "to help bring Amateur Radio into the twenty-first century."

Internet Threats and Regulation

Some 10-20 years ago there were many private networks for automated teller machines, telephone, merchant credit card verification and so forth.  Now most of this all happens over the internet.  If there were some sort of major internet outage or attack, many day-to-day things would be interrupted.

At the same time many ham radio systems use the internet for wormhole-like connectivity.  APRS, WinLink, D-Star, IRLP, Echolink and so forth.  An emphasis on building our own backbone and infrastructure is just simply not there.  This leaves vulnerabilities in our emergency communications reliability.

There are some unknown vulnerabilities in the upcoming switch to IPV6, such as distributed denial of service attacks on IPv4 to IPv6 gateways.  As well as root nameservers, and core internet routing.  

In January 2011 due to protests in Egypt, the Egyptian government ordered service providers to shut down all international connections to the Internet.  Which showed to have a crippling effect on a modernizing economy. 

Simultaneously, the United States is debating a bill to create an Internet kill switch, also known as the PCNAA bill.  In conjunction with this there was a bill (H.R. 607 Broadband for First Responders Act of 2011) that posed a threat to the lower part of the 70 cm band.  The proposal was that the Dept. of Homeland Security was going to in-effect build a 400 MHz WiFi network, for if the switch was ever thrown.

Fortunately, Bill HR 607 looks defeated.  But obviously if we as amateurs could do this, it would be an asset (in the event of), and at no cost to the taxpayer, unlike the Dept of Homeland Securities proposed implementation.

Another thing to point out is that the government is hiring "hackers" (reportedly 1,500 of them), probably because many predict the internet will be the target of future terrorist activities, and wars will be fought over it.  And in 2011, White  House Cybersecurity Coordinator Howard A. Schmidt (W7HAS), states, "The White House is looking for ways that the great work of Amateur Radio operators can continue to support emergencies in the future with particular attention to increased use and dependency on internet based technologies."

For true redundancy, a non-critical network can and should be built by the amateur service to avoid this single point of failure.

I know it sounds crazy, since many of us still do very little on-line checking and that sort of thing. But if you can take down the internet, or majorly cripple it, online stock trading and banking transactions are all transported over the internet, as well as a large portion of phone calls. That would have a major impact on the economy. I encourage you to take a moment and read up on the Egypt thing that happened a while back.

Ham radio used to be a good starting place for many who later entered broadcast and electronics careers.  Today those positions are few and far between due to disposable electronics and consolidation of engineers with mega broadcast groups.  What is the most notable/abundant "tech" career today is IT (information technology) work.    Building these networking helps ham radio stay relevant.  These networks have the potential to draw new blood into the hobby.  New hams who have software skills that can help the community with software defined radio and so forth.

The Need for Speed and Digital Networks

Nearly 10 years ago a survey conducted by the ARRL Technology Task Force, of League members and other amateurs revealed that the number one interest in new technologies was in high-speed digital networks.  Amateur radio, particularly EmComm (this was just after 911), needed some means of data transmission significantly faster than conventional packet radio.  

Winlink is severely limited in capabilities and doesn't necessarily even conform to Internet Engineering Task Force (IETF) standards.

John Champa, K8OCL was the chairman of the ARRL High Speed Multi-Media working group that ran from 2001-2007.  John and his group showed ham radio operators that consumer off-the-shelf 802.11 hardware could be used under Part 97.

There have been some recent threats to the 70cm band with the proposed HR 607 bill. (Feb 2011)

My logic to protecting the spectrum available to us, is to try and make better use of what we have, instead of letting it sit idle.

So following that logic, most of the lower part of the 70 centimeter ham band has been fairly idle.  There is absolutely no reason existing ATV and HSMM cannot co-exist.

So far there seems to be a fair number of hams interested in 802.11 based networks. But one of the big hurdles is understanding and overcoming the line of site, and other wide-band microwave propagation issues.

I've pointed out that 3 GHz is a great band since you won't be sharing the space with all kinds of other Part 15 unlicensed devices that inevitably lead to a higher noise floors and headaches.

The concept of HSMM on the 70 cm band intrigues me and others greatly because of the non-line-of-site possibilities.

My Recommendations

I feel that a better option for the future of Amateur Television is to look towards a high-speed multi-media based solution that will allow Amateurs the flexibility to send images as well as audio and data.  The price of such technologies is far less expressive than standard DTV equipment.

To help fellow amateurs work towards something of this nature, I tend to think the 56 kb / 100 khz rule should be done away with for 70 cm.  Just one band higher, these data bandwidth/data rates are non-existent.  In its current form it also prohibits most modern forms of Digital Amateur Televsion on 70cm.

I'd really like to see some sort of thought at a national level put into revamping some of the band plans.  Honestly I thought there would have been some formal discussion on this already.

I'd like to see some encouragement at a national level (TAPR or the ARRL) to document a bi-directional amplifier in one of the various amateur magazines. Since there are more non-overlapping channels on the 5 GHz and 900 MHz band I would encourage it to be for either of those bands, or 3 GHz.

It's also feasible to imagine that future D-Star radios could incorporate the high-speed digital data mode (128 kbps - that is presently only available on 1.2 GHz due to the present regulations) on the 70cm band.

At Dayton 2012, a new company North-West Digital Radio presented a prototype of just that.  The Universal Digital Radio (aka UDR56K) is a high speed 70cm data radio.

Sadly, thus far I have seen little efforts in this area.  I feel that relaxing the rules a bit will help encourage experimentation and development to foster new uses for the lower portion of the 70cm band, thusly helping protect the spectrum.  

While I feel there are enough loopholes, I'm well aware that some FCC rules petitions have been in the process for years.  I think if several of us were to apply for STA's, this might help expedite this, or at least help build the case for rule modification.

Excerpt from 73 Magazine, August 1985.. QRX Column edited by Perry Donham KW1O:

"DON'T BE A PROBLEM," said FCC Commissioner Ray Kowalski to a conference of repeater coordinators at the Dayton Hamvention. Kowalski, addressing a forum on VHF spectrum management, made it clear that he is concerned about the future of amateur radio. "The current political mode for dealing with problems is to get rid of them," he explained. "You are sitting on very valuable spectrum. There are sharks out there who have mentioned that spectrum and would love [to have] it. Think on how it plays in the halls of the FCC if someone says, 'This has become a problem service; let's get rid of it. It will go away and we can give that spectrum to people who need it [instead] of a bunch of hobbyists.' That's how it will play if it comes down to a solution to solve a problem. Do not become a problem." More specifically, the Commissioner chided hams for running so quickly to the FCC with every little problem. Kowalski reminded the group that amateur radio is a self-policing service and that we should be able to solve our problems with a minimum of regulatory action. "Don't come running to us for some kind of policy or rulemaking. . .you won't like the solution!"

If you agree with the logic that I have stated here, I encourage you to be proactive and drop a line to your section manager or other division director on the subject.  Or if you plan to participate with active experimentation, reportedly Dan Henderson, N1ND at ARRL headquarters can provide anyone with the necessary information to develop and file STA application with the FCC.  Bear in mind that special temporary authorization bears a $60 filing fee, and are only good for 6 months.

[Update Oct 2013]

In October 2013, the ARRL proposed to modernize the rules for data transmissions.  The baud rate limits will be removed, and will governed by just the maximum bandwidth portion of the existing rules.

End the end of December the League’s petition toped the FCC’s “Most Active Proceedings” list. As of the December 23 comment deadline, more than 850 comments had been filed, which is a large number indicating that the issue of data communications is an important one in the Amateur Radio Service.  The majority of the filed comments are supportive of the proposals in the Petition.



Steve, KB9MWR


(1) What Bands Available? (Happenings) - Page 67 March 1959 QST

(2) 1.8 Image Communications Handbook

(3) 10.5 Image Communications Handbook

(4) 10.6 Image Communications Handbook

(5) http://www.arrl.org/news/surfin-more-going-atv-digitally and http://www.atco.tv/DVBSDetails.aspx   http://groups.yahoo.com/group/DigitalATV/

(6) Experimental Digital Codes Now Permitted Above 50 MHz (Happenings) -  November QST 1982- Page 56 and FCC Releases Official Wording of New ASCII Rules (Happenings) - QST April 1980, Page 74



http://www.arrl.org/news/arrl-executive-committee-okays-filing-symbol-rate-rule-modernization-petition  10/15/13