QRSS - Revision history

TimVK4YEH: added qrss grabber info

2011-01-13T06:23:04Z

added qrss grabber info

← Older revision		Revision as of 23:23, 12 January 2011
Line 27:		Line 27:

	QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system (as the same demodulation techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber).		QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system (as the same demodulation techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber).

			== QRSS Grabbers==

			A QRSS grabber is a dedicated receiver that collects and decodes qrss signls.

			Information about how to set up a grabber can be found [http://knightsqrss.blogspot.com/2010/11/howto-setup-qrss-grabber.html Here]

			A compendium of grabbers can be found [http://www.google.com/search?hl=&q=qrss+grabber+compendium&sourceid=navclient-ff&rlz=1B2GGGL_enAU204AU205&ie=UTF-8&aq=1&oq=qrss+grabber here]

	== External links ==		== External links ==

Carlb: link Q-code

2009-04-16T22:13:11Z

link Q-code

← Older revision		Revision as of 15:13, 16 April 2009
Line 1:		Line 1:
	'''QRSS''' is a [[Morse code\|CW]] mode in which the receiver bandwidth is drastically reduced and the rate at which code is sent is slowed beyond that which would be normally be readable by ear.		'''QRSS''' is a [[Morse code\|CW]] mode in which the receiver bandwidth is drastically reduced and the rate at which code is sent is slowed beyond that which would be normally be readable by ear. It is named for QRS, a [[Codes_and_Alphabets#Q-Code\|Q-code]] indicating "send more slowly".

	As received noise is directly proportional to receiver bandwidth, use of bandwidth far less than 1Hz is common in QRSS. This primarily serves the needs of [[QRP]] operation, as it allows extremely weak signals to be received and decoded in the presence of high levels of background noise.		As received noise is directly proportional to receiver bandwidth, use of bandwidth far less than 1Hz is common in QRSS. This primarily serves the needs of [[QRP]] (low-power) operation, as it allows extremely weak signals to be received and decoded in the presence of high levels of background noise.

	[[Morse code]] dot lengths of anywhere from a few seconds to a minute or more have been successfully employed; while a significant improvement in weak-signal performance is observed, the amount of data transferred is severely constrained.		[[Morse code]] dot lengths of anywhere from a few seconds to a minute or more have been successfully employed; while a significant improvement in weak-signal performance is observed, the amount of data transferred is severely constrained.

Carlb: /* Applications */

2009-04-16T22:09:53Z

Applications

← Older revision		Revision as of 15:09, 16 April 2009
Line 26:		Line 26:
	QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength where most practical transmitting loops provide just a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.		QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength where most practical transmitting loops provide just a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.

	QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system (as the same techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber).		QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system (as the same demodulation techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber).

	== External links ==		== External links ==

Carlb: /* Applications */

2009-04-16T22:09:34Z

Applications

← Older revision		Revision as of 15:09, 16 April 2009
Line 26:		Line 26:
	QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength where most practical transmitting loops provide just a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.		QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength where most practical transmitting loops provide just a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.

	QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system. (~~The~~ same techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber.)		QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system (as the same techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber).

	== External links ==		== External links ==

Carlb: /* Applications */

2009-04-16T22:08:11Z

Applications

← Older revision		Revision as of 15:08, 16 April 2009
Line 24:		Line 24:

	== Applications ==		== Applications ==
	QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength ~~for which~~ most transmitting loops ~~can~~ provide a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.		QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength where most practical transmitting loops provide just a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.

	QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system. (The same techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber.)		QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system. (The same techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber.)

Carlb: /* External links */

2009-04-16T22:06:54Z

External links

← Older revision		Revision as of 15:06, 16 April 2009
Line 25:		Line 25:
	== Applications ==		== Applications ==
	QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength for which most transmitting loops can provide a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.		QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength for which most transmitting loops can provide a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.

			QRSS techniques have been applied to other digital and facsimile modes, including the Hellschreiber frequency-vs-time facsimile plotting system. (The same techniques which apply to the CW "curtain" and "waterfall" graphs apply to Hellschreiber.)

	== External links ==		== External links ==
	<!- http://www.maxim-ic.com/glossary/index.cfm/Ac/V/ID/700/Tm/QRSS claims QRSS to be "Quasi-Random Signal Source"; http://myspace.voo.be/pcoupard/qrss_over_ip claims to run QRSS over broadband IP -->		<!-- http://www.maxim-ic.com/glossary/index.cfm/Ac/V/ID/700/Tm/QRSS claims QRSS to be "Quasi-Random Signal Source"; http://myspace.voo.be/pcoupard/qrss_over_ip claims to run QRSS over broadband IP -->
	* [http://www.qrss.thersgb.net What is QRSS?, Receiving QRSS, Transmitting QRSS], M0AYF		* [http://www.qrss.thersgb.net What is QRSS?, Receiving QRSS, Transmitting QRSS], M0AYF
	* [http://www.qsl.net/on7yd/136narro.htm Extreme narrow-bandwidth techniques], ON7YD		* [http://www.qsl.net/on7yd/136narro.htm Extreme narrow-bandwidth techniques], ON7YD

Carlb: New page: '''QRSS''' is a CW mode in which the receiver bandwidth is drastically reduced and the rate at which code is sent is slowed beyond that which would be normally be readable b...

2009-04-16T22:03:47Z

New page: '''QRSS''' is a CW mode in which the receiver bandwidth is drastically reduced and the rate at which code is sent is slowed beyond that which would be normally be readable b...

New page

'''QRSS''' is a [[Morse code|CW]] mode in which the receiver bandwidth is drastically reduced and the rate at which code is sent is slowed beyond that which would be normally be readable by ear.

As received noise is directly proportional to receiver bandwidth, use of bandwidth far less than 1Hz is common in QRSS. This primarily serves the needs of [[QRP]] operation, as it allows extremely weak signals to be received and decoded in the presence of high levels of background noise.

[[Morse code]] dot lengths of anywhere from a few seconds to a minute or more have been successfully employed; while a significant improvement in weak-signal performance is observed, the amount of data transferred is severely constrained.

Due to the narrow bandwidth used, frequency stability is critical at both the receiver and transmitter. A crystal-controlled reference using a crystal oven to maintain constant temperature is therefore recommended.

== Fast Fourier Transform demodulation ==
Mathematically, a fast Fourier transform is a calculation which, given a digitized waveform (vs. time) as input, calculates the signal strength at each frequency in the sample. By connecting an SSB receiver to a computer sound card, a received signal may be captured and the signal level at each frequency displayed vs. frequency and time by software.

A computer may store a received signal and replay it at a faster speed; it may also be used (with FFT software) to generate a "waterfall" or "curtain" display graphically. Brightness or colour may be used to indicate signal strength while X:Y axes represent time and frequency. (Axes are assigned so that time runs horizontally for a "curtain" graph and vertically for a "waterfall" - the two graphical depictions are otherwise identical).

As FFT demodulation of CW allows multiple frequencies within the passband to be monitored and displayed simultaneously, it will display a received signal even in the case of frequency drift and can display multiple adjacent-channel signals side-by-side if all fall within the passband.

== Dual-frequency CW ==
The timing for standard International Morse code is:
* Dot: one dot-time "on", followed by one dot-time "off"
* Dash: three dot-times "on", followed by one dot-time "off"
* The space between characters is three dot-times "off"
* The space between words is seven dot-times "off"

A dash (including inter-symbol spacing) therefore takes twice as long to send as a dot. One approach used in QRSS is a non-standard system in which a dot and a dash are the same length but are transmitted on slightly-different frequencies. This scheme permits the time between individual symbols to be reduced, as well as reducing the length of a dash - but at the cost of allowing slightly-wider bandwidth. As two frequencies are used, each of the pair is subject to noise and interference.

== Applications ==
QRSS has served primarily in applications such as CW beacons, where only relatively small amounts of data need be transmitted. While it has been used on various HF bands, it is most useful on bands where radioamateur allocations are very narrow or strictly limited in power (such as the 136kHz allocation in the United Kingdom, cited as having stringent power limits, a very limited bandwidth and a 2200-metre wavelength for which most transmitting loops can provide a small fraction of one percent of power efficiency). Transmitters are typically small QRP or QRPp devices of home-brew design; some stations have used 1 RPM clockwork as a motor to turn a mechanical disk on which a beacon's callsign is encoded.

== External links ==
<!- http://www.maxim-ic.com/glossary/index.cfm/Ac/V/ID/700/Tm/QRSS claims QRSS to be "Quasi-Random Signal Source"; http://myspace.voo.be/pcoupard/qrss_over_ip claims to run QRSS over broadband IP -->
* [http://www.qrss.thersgb.net What is QRSS?, Receiving QRSS, Transmitting QRSS], M0AYF
* [http://www.qsl.net/on7yd/136narro.htm Extreme narrow-bandwidth techniques], ON7YD
* [http://www.hanssummers.com/radio/qrssjb/index.htm QRSS junkbox beacon], G0UPL
* [http://www.ussc.com/~turner/qrss1.html QRSS and you]
* [http://www.w0ch.net/qrss/qrss.htm QRSS], W0CH
* [http://g4oep.atspace.com/qrss/qrss.htm QRSS], G4OEP
* [http://www.users.on.net/~davroz/vk6di/ Weak Signal and QRSS Web page] VK6DI

{{modes}}