ROS and CHIP deemed illegal below 222 mHz for U.S. amateurs
It appears as though neither ROS or the older CHIP digital modes are legal for use below 222 mHz by licensed U.S. amateurs.
On 23 February, 2010, an email was shared on various Web sites in which Dan Henderson of the ARRL reported that the League’s technical staff had determined that the new ROS mode did, indeed, include spread spectrum technology and, as a result, was illegal for use below 222 mHz by licensed U.S. amateurs.
As a result of that email, I contacted the FCC and formally requested a review of ROS. Here is the full text of my request and the FCC’s response:
The case you submitted via the FCC has been resolved. The resolution details for Case ID HD0000001311853 are below.
If you have any questions contact us at (877) 480-3201.
Summary* : Request for clarification of new amateur radio digital mode
Description* : Within the past week, a new digital mode - called ROS - has surfaced on the HR amateur bands. Its creator refers to it as spread spectrum, but there is some debate over whether the mode truly represents spread spectrum as defined by the FCC. I am writing to request a review of the creator's documentation, which I have attached, and a formal ruling on whether this mode is legal for use below 222 mHz by licensed U.S. amateurs. It would be very helpful if the FCC, upon completion of this review, would distribute a public announcement of its determination to appropriate amateur radio and media outlets. Thank you very much in advance for your time and prompt attention to this request. I look forward to hearing from you soon.
Timothy J. Lilley - N3TL
Solution Details : Dear Mr. Lilley,
Section 97.305 is the rule that specifies where different emission types are allowed to be transmitted on different bands. "ROS" is viewed as "spread spectrum," and the creator of the system describes it as that. We assume that he knows what he created. 97.305 authorizes spread spectrum emission types (defined in Section 97.3) to be transmitted by FCC licensed amateur stations at places we regulate communications only on 222-225 MHz and higher frequency amateur bands. European telecommunication regulatory authorities may authorize amateur stations in Europe to use SS on the HF bands, but this is of no concern to us. The Commission does not determine if a particular mode "truly" represents spread spectrum as it is defined in the rules. The licensee of the station transmitting the emission is responsible for determining that the operation of the station complies with the rules. This would include determining the type of emission the station is transmitting and that the frequencies being used are authorized for that type of emission.
Should you have any further questions, or need additional information, please contact the ULS Customer Support Hotline at (877) 480-3201, selecting option 2.
On 25 February, 2010, I contacted Mr. Henderson and requested a review of the CHIP mode by the ARRL technical staff. Here is the complete text of that request and Mr. Henderson’s response, which appears first:
We read the information and reviewed the CHIP64 information yesterday and have come to the same place as with ROS - it is spread spectrum and isn't legal below 222 MHz.
Thanks and 73
Dan Henderson, N1ND
Regulatory Information Manager
ARRL, the national association for Amateur Radio™
From: Tim - N3TL [mailto:firstname.lastname@example.org]
Sent: Thursday, February 25, 2010 12:03 PM
To: Henderson, Dan N1ND
Subject: Request for technical review
In light of your recent actions to have ARRL technical staff review the new ROS mode for legality below 222 mHz for licensed U.S. amateurs, I am writing to formally request a similar review by ARRL technical staff of the CHIP mode. To help in that review, I am attaching the PDF document that the mode’s creator - Antonio Porcino, IZ8BLY – currently has posted on his Web site for the mode.
Based on the FCC response to my inquiry about ROS on Feb. 23rd, it seems clear to me that the CHIP mode also is illegal for use below 222 mHz by licensed U.S. amateurs. As the FCC agent noted in that response, “’ROS’ is viewed as ‘spread spectrum,’ and the creator of the system describes it as that. We assume that he knows what he created.”
In the attached document, Mr. Porcino clearly and inarguably refers to the CHIP mode as spread spectrum. As a result, it seems to me that if ROS is illegal for U.S. amateurs below 222 mHz, then CHIP also is.
For that reason, I am asking you to take the same steps with ARRL technical staff that you took earlier this week regarding ROS. I am interested to learn whether the League’s technical staff concurs with the mode’s creator that it is, indeed, using spread spectrum technology. If the answer is no, then I further request a clear explanation of why ROS is SS and CHIP is not.
Please contact me at your convenience if you have any questions or need additional information. I look forward to hearing from you.
Timothy J. (Tim) Lilley – N3TL
ARRL Member No. 0007027180
Based on the language of the FCC response, I see no need to seek a similar review of CHIP from the Commission. It makes clear that the FCC assumes that software developers know what they created, and the creator of CHIP clearly describes it in the PDF available on his Web site as using spread spectrum technology.
I believe it important to share this information with the amateur community. I thank Mr. Henderson and the ARRL – and the FCC – for prompt responses to my requests.
Tim – N3TL
Below is a copy of the technical description, as posted on the program's website.
I should note Agent 3820 did not rule conclusively that ROS is spread spectrum unequivocally. He included in his letter:
The FCC also did not disclose how they reached their conclusion. Was it merely a glance at the provided documents? Did they do extensive spectral analysis? The text outlined in red above simply emphasizes that the FCC is giving a "hands off" approach to this issue. I say the issue is a delicate one ,involving a close examination of the exact algorithm used
The Commission does not determine if a particular mode "truly" represents spread spectrum as it is defined in the rules. The licensee of the station transmitting the emission is responsible for determining that the operation of the station complies with the rules. This would include determining the type of emission the station is transmitting and that the frequencies being used are authorized for that type of emission.
Below is text from the currently available technical description found on the program author's site under "ROS Technical Description v1.0″
ROS Technical Description
By Jose Alberto Nieto Ros
ROS is a easy interface chat mode for real-time amateur contacts. It is a half-duplex non-Automatic Repeat ReQuest (ARQ) forward-error-correcting (FEC) mode. It performs well on long-path fading conditions and in the presence of interference.
The transmission is based on M-FSK (sequential single tone FSK), with continuous phase (CPSK) tones. There is no delay between tones, and no shaping of the tones (rectangular window).
The ROS transmission system is divided by frames of tones. A Frame is formed by 144 tones: 128 tones for data (with 7 bits Gray Code), and 16 tones for synchronization.
128MFSK offers very good immunity to interference and ionospheric effects, and is also very sensitive. However, you can have a wonderful modulation that does not work if the timing is not perfect, even with a good FEC.
ROS has solved that problem by using an alternative to the classical PLL structure. This system uses 16 tones of synchronization, and they are known in advance by the receiver. ROS is tested that can perform synchronization of data in very poor conditions of noise, even with a strong multi-path. This allows the modulation 128FSK able to do their job properly because you always know where it begins and ends a symbol. Also ROS can support up to 200Hz shifts (in real time). Synchronization is the main virtue of this mode.
Before transmitting data, a known sequence of 20 symbols is sent to the receiver know the exact time to start decoding. The receiver starts to decode only if at least 12 of 20 possible symbols have arrived properly. You can see this measure in the frame acquisition gauge.
After transmitting data, another sequence of 16 symbols is sent to the receiver know the exact time to stop decoding. The message will appear on the screen.
Symbol Rate and Tone Spacing
The system uses two symbol rates. Each symbol consists of a single square keyed pulse with the same start and finish phase as all others. In the case of 16 baud (15.625), tone spacing is numerically equal to the symbol rate: 15.625 Hz. In the case of 1 baud (0.9765 baud), tone spacing is numerically equal to the Symbol Rate x 16: 15.625 Hz.
Mode at 1 baud is intended for use with weak signals in difficult environments.
Transmission bandwidth are 144x16.125=2250 Hz. The transmitter does not need to be linear. You can use Class C Amplifiers.
FEC coding with interleaver is used in ROS mode. FEC is sequential R=1/2, K=7, using NASA algorithms.
Convolutional interleavers has been proposed by Ramsey  and Forney . The code symbols are sequentially shifted into de bank of 16 registers; each successive register provides 1 symbol more storage than did the preceding one. The important advantage of convolutional over block interleaving is that with convolutional interleaving the end-to-end delay is M(N-1) symbols, where M=NJ, and the memory required is M(N-1)/2 at boths ends of the channel. Therefore, there is a reduction of one-half in delay and memory over the block interleaving requirements.
The alphabet coding in the 16 bauds mode is the IZ8BLY Varicode, using an extended ASCII character set and super-ASCII control codes. The alphabet coding in the 16 bauds mode are a 6 bits ASCII.
The receiver uses non-coherent demodulation, employing an FFT filter as demodulator technique
Signal is integrating over the symbol tone period. In the case of 16 bauds mode, symbol period is of 64 mseg. In the case of 1 baud mode symbol period is of 1024 mseg.
A recovered symbol clock algorithm is used to maintain synchronism.
The FEC decoder uses soft decisions, but, unlike other implementations of the Viterbi algorithm, the implementation in the ROS mode works directly with symbols instead of bits in the trellis diagram. That provides you greater robustness in the decoding.
 Ramsey, J.L., “realization of optimum Interleavers, IEEE Trans. Inf. Theory, vol. IT16, no. 3, May 1970, pp 338-345
Forney, G.D., “Burst-Correcting Codes for the Classic Bursty Channel,” IEEE Trans. Commun. Technol, vol. COM19, Oct 1971pp. 772-781
What about HamDRM
I don't precisely know the technology under ROS/CHIP, but given the description it is similar to HamDRM which use COFDM multiplex.
Does someone know how is considered this transmission mode by ARRL ?
Yan - XV4TUJ.
OFDM is legal in the USA on HF. ROS is legal, because it is MFSK. CHIP64 is legal, because the RF is n't spread-spectrum, only the audio uses a spread-spectrum technique.
Originally Posted by K5OKC
I agree with you, it is audio spread spectrum not baseband spread spectrum. The modulation by itself is still SSB.
The problem could be when people don't set their AF gain in a good manner creating splatter because of an overdriven PA.
But this also occurs in phone SSB sometime... (I have some "neighbours" wasting 10KHz when they turn on their 1kw amplifier).
KE7HQY wrote: "Below is a copy of the technical description, as posted on the program's website."
The ORIGINAL technical document carried this Title:
“INTRODUCTION TO ROS: THE SPREAD SPECTRUM”
Further that document included this statement: “ROS uses a Spread Spectrum technique known as Frequency-hopping spread spectrum (FHSS).”
If KE7HQY – or anyone else reading this – cares to email me (address is good on my page here at QRZ.com), I will gladly provide a copy of that ORIGINAL technical description of the mode, which Jose removed from his Web site after the ARRL and FCC weighed in on ROS a few days ago.
Further, please note the following from the first page of the description of CHIP64 provided by its creator, Antonino Porcino, IZ8BLY, on the Web site he created for that mode: "Chip64 uses the so called Direct Sequence Spread Spectrum (DSSS)."
KE7HQY wrote: "The FCC also did not disclose how they reached their conclusion."
I respectfully disagree. Please read again this comment from the text of the FCC response:
"'ROS' is viewed as 'spread spectrum,' and the creator of the system describes it as that. We assume that he knows what he created."
I posted this information to QRZ.com because:
1 - FCC rules obligate licensed U.S. amateurs to operate a station that complies with the rules.
2 - That compliance includes responsibility for determining that the frequency in use is legal for U.S. amateurs, and that the mode transmitted on that frequency is legal for use on that frequency by U.S. amateurs.
3 - FCC rules outlaw the use of spread spectrum modes below 222 mHz.
4 - The creators of ROS and CHIP specifically refer to them - or have referred to them - as using spread spectrum technology.
Because of Nos. 1 and 2 above, I consider it my responsibility to operate the N3TL station within the FCC rules, and to make sure the modes I transmit are legal for use on the frequency I choose.
Each of us must decide whether ROS or CHIP is legal for us to use in transmissions from our respective stations on frequencies below 222 mHz.
Because of the information I have obtained over the past week from the FCC and the ARRL, I am not operating ROS or CHIP below 222 mHz here at the N3TL station. When it comes to potentially risking my amateur license, I choose to err on the side of caution.
That is MY choice. YOUR choice may differ, and you are entitled to it.
73 to all,
Tim - N3TL
I encourage you to contact the ARRL and FCC with this, and formally request further review of their previous decisions.
Originally Posted by K5OKC
I have nothing against either ROS or CHIP. On the contrary, I wish the modes - especially ROS - were legal for HF use in the U.S. I started this post only to assure that U.S. amateurs had this information from the ARRL and the FCC as they decided whether to use either mode below 222 mHz at their stations.
Again, I encourage you (or anyone who shares your view) to do what I did - contact the ARRL and FCC, and formally request further review of their determinations.
Tim - N3TL
As far as I can tell neither ARRL or the FCC did their technical due diligence. They both basically assumed because the ROS creator says the mode is spread spectrum that it is, therefore it's illegal below 222 Mhz. End of story. I can write a specification for a mode that is technically AM and call it CW, but that doesn't make it CW or legal in CW bands.
ROS is clearly MFSK. With what is commonly accepted as a frequency hopping spread spectrum system, the frequency of a particular hop instance or the hop sequence itself doesn't carry intelligence. With ROS it clearly does. In FHSS the modulation on the hopping carrier carries the intelligence. As far as I can tell, with ROS the carrier itself isn't modulated. Using the same logic that has determined ROS is spread spectrum, RTTY would be considered spread spectrum, too.
I'm disappointed in ARRL. I am with the FCC as well, however that's been par for the course with them on the technical side of the house for years.
I think this whole issue is much ado about nothing. If someone uses a digital mode however it modulates, if it stays within a given bandwidth, what does it matter? I know there's been angst over ROS interfering with the beacon network and ROS on ROS QRM, but that's not a function of the modulation.
If one looks at Part 97, the language on just what is spread spectrum is incredibly vague. I doubt the intent of the language prohibiting SS on frequencies below 222 Mhz was to keep a 2 khz or so wide digital mode off of HF.
For the record I've never tried ROS and I doubt I will, I just see this as being a technicality fishing expedition that's not going to have any benefit. It's great that we're self-policing and hopefully that will continue for years to come. It's clear from the FCC non-answer that we should probably just let sleeping dogs lie. Perhaps I'm wrong, but I think FCC staffers are out of touch with amateur radio and we need to forge our own path ahead, and avoid involving the FCC wherever possible.
"[I]You are never dedicated to something you have complete confidence in. No one is fanatically shouting that the sun is going to rise tomorrow. They know it's going to rise tomorrow. When people are fanatically dedicated to political or religious faiths or any other kinds of dogmas or goals, it's always because these dogmas or goals are in doubt.[/I]"
- Robert M. Pirsig
Zen and the Art of Motorcycle Maintenance
[I]Asteroids and global warming: God's way of wiping out civilizations with lousy space programs and a disdain for science.[/I]
Originally Posted by K3NG
I ask you, sir, to do what I did - contact the League and the Commission; state your case; and formally request review and clarification. A lot of people are offering arguments here and elsewhere concerning the potential legality of ROS, in particular, and CHIP below 222 mHz for U.S. amateurs.
However, since no one has added, with those arguments, that they intend to present them to either ARRL or the FCC, I can't accept them and change my decision to not operate the modes below 222 mHz.
We are, indeed, self-policing; but we do not set the rules.
Tim - N3TL
In the best case, the ROS emission type is SSB using 128 channels to convey data, J7D, which is not a specifically authorized data mode according to Part 97.3(c)(2) of the Rules, so it would not qualify as 97.309(b) unspecified data code, and is 97.307(f)(8) data, only authorized on 1.25m and above by 97.305(c). Based on the description of ROS provided, it appears to be a multiplex emission which could be JXX spread spectrum. However, automatic transmission power adjustment needed to reduce co-channel interference is not addressed as required by 97.311(d), so ROS wouldn't meet the FCC requirements for even that emission type.
Originally Posted by XV4TUJ
Anyone else read the rules differently?
Last edited by KD6KXR; 02-27-2010 at 04:24 PM.