Let's say you have a radio transmitter and a receiver that our both tied to a standard reference. ie a GPS disciplined rubidium. The transmitter transmits a narrow BPSK signal at a predetermined RF frequency, and since the receiver knows what that frequency is, can narrow in, sample and analyze the hell out of this band. The receiver can then detect and demodulate a very weak signal well below the noise floor. What is the name for this type of detection/gain technique, when a receiver knows the exact frequency of the transmitter and therefore can receive information below the noise floor? Does anyone know of any papers or websites relating to this topic? Thomas
Name that Gain
Started by ●March 2, 2006
Reply by ●March 2, 20062006-03-02
"Thomas Magma" <somewhere@overtherainbow.com> wrote in message news:iLGNf.85463$sa3.34341@pd7tw1no...> Let's say you have a radio transmitter and a receiver that our both tied > to a standard reference. ie a GPS disciplined rubidium. The transmitter > transmits a narrow BPSK signal at a predetermined RF frequency, and since > the receiver knows what that frequency is, can narrow in, sample and > analyze the hell out of this band. The receiver can then detect and > demodulate a very weak signal well below the noise floor. > > What is the name for this type of detection/gain technique, when a > receiver knows the exact frequency of the transmitter and therefore can > receive information below the noise floor? > > Does anyone know of any papers or websites relating to this topic? >Processing gain Best of luck - Mike
Reply by ●March 2, 20062006-03-02
"Thomas Magma" <somewhere@overtherainbow.com> wrote in message news:iLGNf.85463$sa3.34341@pd7tw1no...> Let's say you have a radio transmitter and a receiver that our both tied > to a standard reference. ie a GPS disciplined rubidium. The transmitter > transmits a narrow BPSK signal at a predetermined RF frequency, and since > the receiver knows what that frequency is, can narrow in, sample and > analyze the hell out of this band. The receiver can then detect and > demodulate a very weak signal well below the noise floor. > > What is the name for this type of detection/gain technique, when a > receiver knows the exact frequency of the transmitter and therefore can > receive information below the noise floor? > > Does anyone know of any papers or websites relating to this topic? > > Thomas>when a receiver knows the exact frequency of the transmitter and therefore >can receive information below the noise floor?Any sensible radio? Fred
Reply by ●March 2, 20062006-03-02
"Fred Marshall" <fmarshallx@remove_the_x.acm.org> wrote in message news:b7Kdnd6OD8yAEZrZnZ2dnUVZ_smdnZ2d@centurytel.net...> > "Thomas Magma" <somewhere@overtherainbow.com> wrote in message > news:iLGNf.85463$sa3.34341@pd7tw1no... >> Let's say you have a radio transmitter and a receiver that our both tied >> to a standard reference. ie a GPS disciplined rubidium. The transmitter >> transmits a narrow BPSK signal at a predetermined RF frequency, and since >> the receiver knows what that frequency is, can narrow in, sample and >> analyze the hell out of this band. The receiver can then detect and >> demodulate a very weak signal well below the noise floor. >> >> What is the name for this type of detection/gain technique, when a >> receiver knows the exact frequency of the transmitter and therefore can >> receive information below the noise floor? >> >> Does anyone know of any papers or websites relating to this topic? >> >> Thomas > >>when a receiver knows the exact frequency of the transmitter and therefore >>can receive information below the noise floor? > > Any sensible radio? > > FredBut I didn't answer the question and Mike did. There is a fairly well accepted system model that can include things like the source, the source antenna, the medium, the receive antenna, the receiver and the detector perhaps. The receiver provides the processing gain dependent on the signal characteristics and the noise. You might look for Receiver Operating Characteristic or Curve or ROC. It's common to express each part in terms of dB and then add them all together. Fred
Reply by ●March 3, 20062006-03-03
"Mike Yarwood" <mpyarwood@btopenworld.com> wrote in message news:du7fj4$h1d$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...> > "Thomas Magma" <somewhere@overtherainbow.com> wrote in message > news:iLGNf.85463$sa3.34341@pd7tw1no... >> Let's say you have a radio transmitter and a receiver that our both tied >> to a standard reference. ie a GPS disciplined rubidium. The transmitter >> transmits a narrow BPSK signal at a predetermined RF frequency, and since >> the receiver knows what that frequency is, can narrow in, sample and >> analyze the hell out of this band. The receiver can then detect and >> demodulate a very weak signal well below the noise floor. >> >> What is the name for this type of detection/gain technique, when a >> receiver knows the exact frequency of the transmitter and therefore can >> receive information below the noise floor? >> >> Does anyone know of any papers or websites relating to this topic? >> > Processing gain > > Best of luck - Mike > >Maybe it's not "gain" that I'm describing, but a form of detection. I understand that processing large amounts of samples will reduce the noise floor of a radio receiver. However, knowing exactly where to look in the spectrum has certain advantages over other radio receivers. There is no longer a need for a search and verification algorithm. Something that is extremely hard to do when the transmitted signal is a burst of RF data.
Reply by ●March 3, 20062006-03-03
Thomas Magma wrote:> "Mike Yarwood" <mpyarwood@btopenworld.com> wrote in message > news:du7fj4$h1d$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com... > >>"Thomas Magma" <somewhere@overtherainbow.com> wrote in message >>news:iLGNf.85463$sa3.34341@pd7tw1no... >> >>>Let's say you have a radio transmitter and a receiver that our both tied >>>to a standard reference. ie a GPS disciplined rubidium. The transmitter >>>transmits a narrow BPSK signal at a predetermined RF frequency, and since >>>the receiver knows what that frequency is, can narrow in, sample and >>>analyze the hell out of this band. The receiver can then detect and >>>demodulate a very weak signal well below the noise floor. >>> >>>What is the name for this type of detection/gain technique, when a >>>receiver knows the exact frequency of the transmitter and therefore can >>>receive information below the noise floor? >>> >>>Does anyone know of any papers or websites relating to this topic? >>> >> >>Processing gain >> >>Best of luck - Mike >> >> > > > Maybe it's not "gain" that I'm describing, but a form of detection. I > understand that processing large amounts of samples will reduce the noise > floor of a radio receiver. However, knowing exactly where to look in the > spectrum has certain advantages over other radio receivers. There is no > longer a need for a search and verification algorithm. Something that is > extremely hard to do when the transmitted signal is a burst of RF data.Noise power is proportional to bandwidth. The narrower the band, the less the noise. What does noise "floor" mean to you? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●March 3, 20062006-03-03
"Thomas Magma" <somewhere@overtherainbow.com> wrote in message news:9D0Of.96889$H%4.86184@pd7tw2no...> > "Mike Yarwood" <mpyarwood@btopenworld.com> wrote in message > news:du7fj4$h1d$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com... >> >> "Thomas Magma" <somewhere@overtherainbow.com> wrote in message >> news:iLGNf.85463$sa3.34341@pd7tw1no... >>> Let's say you have a radio transmitter and a receiver that our both tied >>> to a standard reference. ie a GPS disciplined rubidium. The transmitter >>> transmits a narrow BPSK signal at a predetermined RF frequency, and >>> since the receiver knows what that frequency is, can narrow in, sample >>> and analyze the hell out of this band. The receiver can then detect and >>> demodulate a very weak signal well below the noise floor. >>> >>> What is the name for this type of detection/gain technique, when a >>> receiver knows the exact frequency of the transmitter and therefore can >>> receive information below the noise floor? >>> >>> Does anyone know of any papers or websites relating to this topic? >>> >> Processing gain >> >> Best of luck - Mike >> >> > > Maybe it's not "gain" that I'm describing, but a form of detection. I > understand that processing large amounts of samples will reduce the noise > floor of a radio receiver. However, knowing exactly where to look in the > spectrum has certain advantages over other radio receivers. There is no > longer a need for a search and verification algorithm. Something that is > extremely hard to do when the transmitted signal is a burst of RF data.If you know precisely when the burst is going to arrive because your source and detector are synchronised to some common source and you are able to determine the propagation delay then you can reduce the amount of processing that you need to do for a given probability of correctly receiving a message (or knowing that your received message has errors) as you don't need to slip your detection window through a whole lot of false alarms and then decide that there is no recognisable message for that position (or horrors! invent a message) - is this the sort of thing you are thinking of? Similarly , if you know your modulation type, exactly what FEC code will be used to transmit a message of a known length at a precisely known rate, what the scrambler and encryption settings are , what the probability of transmission of each symbol is and what the channel distortions are then you can get quite close to the shannon limit without using an awful lot of complicated mutual estimators to guess all of these things - is any of this the sort of thing that is on the tip of your tongue? You seem to be looking for something specific but the closest I can get at the moment is synchronisation. Best of luck - Mike
Reply by ●March 3, 20062006-03-03
> > Noise power is proportional to bandwidth. The narrower the band, the less > the noise. What does noise "floor" mean to you? > > Jerry >Tricky question. In my specific application I typically refer to "noise floor" as being when the noise has more power than the signal (noise + signal) in a standard analog heterodyning radio. I use that as a reference when I design digital radios for the purpose of detecting and demodulating very weak signals.
Reply by ●March 3, 20062006-03-03
Thomas Magma wrote:>>Noise power is proportional to bandwidth. The narrower the band, the less >>the noise. What does noise "floor" mean to you? >> >>Jerry >> > > > Tricky question. In my specific application I typically refer to "noise > floor" as being when the noise has more power than the signal (noise + > signal) in a standard analog heterodyning radio. I use that as a reference > when I design digital radios for the purpose of detecting and demodulating > very weak signals.That depends linearly on the bandwidth (square root of bandwidth for voltage.) I think of the noise floor as the level of the trace on a spectrum analyzer between signals. It's lower for a slow sweep and hence narrow effective filter than for a fast sweep. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●March 5, 20062006-03-05
