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
(3)
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.
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.”
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.
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.
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."
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.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.
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.
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.
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.
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 is May 17, 2012. To look at what others have submitted, search for proceeding number 12-91.
Thanks,
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