unreferenced date October 2008 In telecommunications , falsing describes a decoder assuming that it is detecting a valid input when one is not present. This is also known as a false decode . To make the concepts simpler, this article will discuss analog circuits used before digital signal processing. Examples of decoder falsing include a telephone answering machine detecting dial pulses from a rotary dial as ringing voltage. The result being that the answering machine answers in response to dialing. a two way radio with an enabled CTCSS decoder turns on the receive audio for one or two syllables of a signal with a close in tone frequency, but wrong , CTCSS tone. The person listening to the radio occasionally hears nonsense partial words from the receiver s speaker et ... up ... a ringing signal ringy telephone circuit with SF single frequency signaling and poor level discipline drops calls because it sees harmonic frequencies or the distorted waveform as a valid circuit idle or on hook SF signal. power line transients cause a telemetry decoder to momentarily decode the power line noise as a false turn on command, causing a remote controlled water well pump to cycle on and off needlessly. Analog tone decoders used in telephone and two way radio systems are designed to work in a balance between expensive, complicated filtering and low cost simplicity. The engineering problem is to make ... DC voltage which is used to switch something on or off. Falsing sometimes occurs on a voice circuit ... Hz. Reducing the possibility of falsing Some systems that use tone signaling require higher reliability and less probability of falsing. One method of reducing falsing uses formats with simultaneous ... decoding to a time constraint. In the case of Quik Call I or a string of DTMF digits, the falsing would ... than falsing in a single tone decoder. In two tone sequential, tone and voice radio paging, decoders are actuated by decoding one tone and then a second in the proper sequence. Falsing could only occur ... more details
Single frequency signaling SF is line signaling in telephony in which dial pulse s or line signaling supervisory signals are conveyed by a single voice frequency tone in each direction. SF and similar systems were used in 20th century carrier system s. An SF signaling unit converts direct current DC signaling usually, at least in long distance calling long distance circuits, E&M signaling to a format characterized by the presence or absence of a single voice frequency tone , which is suitable for transmission telecommunications transmission over an alternating current AC path, e.g. , a carrier system . The SF tone is present in the on hook or idle state and absent during the seized state. In the seized state, dial pulses are conveyed by bursts of SF tone, corresponding to the interruptions in dc continuity created by a rotary dial or other DC dialing mechanism. The SF tone may occupy a small portion of the User telecommunications user data channel communications channel spectrum, e.g., 1600 Hz or 2600 Hz SF in band signaling . There may be a notch filter at the precise SF frequency , either filtering the circuit at all times or only when the circuit is off hook , to prevent the user from inadvertently disconnecting a telephone call call if the users voice has a sufficiently strong spectral content at the SF frequency, a falsing condition known as talk off . Notoriously, this property was expoited by blue box ers and other toll fraudsters. The SF tone may also be just outside the user voice band, e.g., 3600 Hz. The Defense Data Network DDN transmitted DC line signaling pulses or supervisory signals, or both, over carrier wave carrier channels or cable pairs on a four wire circuit basis using a 2600 Hz Signalling telecommunication signal tone. The conversion into tones, or vice versa, is done by SF signal units. SF was developed in the early 20th century and standardized in middle century. It declined in the 1970s due to the adoption of T carrier , and was largely aba ... more details
main Signalling telecommunications In telecommunications , in band signaling is the sending of metadata and control signal control information in the same band, on the same channel, as used for data. Telephone For example, when dialing a modern telephone , the telephone number is encoded and transmitted across the telephone line as Dual Tone Multi Frequency DTMF tones. The tones control the telephone system by instructing the telephone company s telephone switch equipment where to route the call to. These control tones are sent over the same channel communications channel and in the same band 300Hz to 3.4kHz as the voice and other sounds of the telephone call. In band signalling is also used on older telephone carrier systems to provide Interexchange carrier inter exchange information on how to route calls. Examples of this kind of in band signalling system are SS5 and R2 signalling R2 . Separating the control signals, also referred to as the control plane, from the data if a Transparency telecommunication bit transparent connection is desired is usually done by Escape sequence escaping the control instructions. Occasionally, however, networks are designed so that data is to a varying degree garbled by the signaling. Allowing data to become garbled is usually acceptable when transmitting sounds between humans, since the users rarely notice the slight degradation, but this leads to problems when sending data that has very low error tolerance, such as information transmitted using a modem . In band signaling is insecure because it exposes control signals, protocols and management systems to the user s , which may result in falsing . In the case of the blue box es that were popular in the 1960s and 1970s, such falsing was deliberate. By using blue boxes to generate the appropriate tones, a caller could abuse functions intended for testing and administrative use to make free long distance calls. Modems may also interfere with in band signaling, so in some countries, a g ... more details
In telephony, Common Channel Signaling CCS , in the US also Common Channel Interoffice Signaling CCIS , is the transmission telecommunications transmission of Signaling telecommunication signaling information control information on a separate channel from the data, and, more specifically, where that signaling channel controls multiple data channels. ref harv Ronayne 1986 p 141 . ref For example, in the public switched telephone network PSTN one channel of a communications link is typically used for the sole purpose of carrying signaling for establishment and Clearing telecommunications tear down of telephone call s. The remaining channels are used entirely for the transmission of voice data. In most cases, a single 64kbit s data link channel is sufficient to handle the call setup and call clear down traffic for numerous voice and data channels. ref harv Ronayne 1986 p 145 . ref The logical alternative to CCS is Channel Associated Signaling CAS , in which each bearer channel has a signaling channel dedicated to it. CCS offers the following advantages over CAS, in the context of the PSTN ref harv Ronayne 1986 p 142 . ref Faster call setup. No falsing interference between signaling tones by network and speech frequencies. Greater trunking efficiency due to the quicker set up and clear down, thereby reducing traffic on the network. No security issues related to the use of in band signaling with CAS. CCS allows the transfer of additional information along with the signaling traffic providing features such as caller ID . The most common CCS signaling methods in use today are Integrated Services Digital Network ISDN and Signaling System 7 SS7 . ISDN signaling is used primarily on trunks connecting end user private branch exchange PBX systems to a central office . SS7 is primarily used within the PSTN. The two signaling methods are very similar since they share a common heritage and in some cases, the same signaling messages are transmitted in both ISDN and SS7. CCS is dist ... more details
about ringing in electronics and signals generally ringing artifacts in signal processing, particularly image processing ringing artifacts File High accuracy settling time measurements figure 1.png thumb An illustration of overshoot signal overshoot , followed by ringing and settle time . In electronics , signal processing , and video, ringing is unwanted oscillation of a signal, particularly in the step response the response to a sudden change in input . It is also known as hunting. It is closely related to overshoot signal overshoot , generally occurring following overshoot, and thus the terms are at time conflated. It is also known as ripple electrical ripple , particularly in electricity or in frequency domain response. Electricity In electricity electrical circuits, ringing is an unwanted oscillation of a voltage or Current electricity current . It happens when an electrical pulse causes the parasitic capacitor capacitances and inductor inductances in the circuit i.e. those that are not part of the design, but just by products of the materials used to construct the circuit to resonance resonate at their characteristic frequency ref Johnson, H and Graham, M. High Speed Digital Design A Handbook of Black Magic 1993. Pgs 88 90 ref . Ringing artifacts are also present in square wave s see Gibbs phenomenon . Ringing is undesirable because it causes extra current to flow, thereby wasting energy and causing extra heating of the components it can cause unwanted electromagnetic radiation to be emitted Citation needed date March 2009 it can delay arrival at a desired final state increase settling time and it may cause unwanted triggering of bistable elements in digital circuit s. Ringy communications circuits may suffer falsing . Ringing can be due to signal reflection , in which case it may be minimized by impedance matching . Video In video circuits, electrical ringing causes closely spaced Ghosting television repeated ghosts of a vertical or diagonal edge where dark c ... more details
Hz on the same channel. The tones are so close that some decoders may periodically Falsing false ... an intermittent signal referred to in the two way field as falsing the decoder . This and other technical ... more details
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