Dtmf Mic
Dtmf Mic
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Yaesu MH-59A8J Remote Control Microphone - For FT-897D & FT-857D $74.99 This is the Full Keypad Remote microphone for the Yaesu FT-857D & FT-897D HF Radios. May work with other models. Not just DTMF, also has Direct Keypad entry & function keys. Genuine Yaesu Product.... |
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Gino DTMF Mic for Yaesu MH-48A6J FT-7800R FT-8800 FT-8900R $28.09 Features RJ11 6 pin plug, it enables you to talk and listen without having to remove the radio from your belt. It is compatible with Yaesu FT-7800R, FT-8800, FT-8900R. This is a non-OEM generic product.... |
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Gino Coil Cord DTMF Microphone for Yaesu FT-7800 FT-8800 FT-8900 $20.41 Features RJ11 6 pin plug, it enables you to talk and listen without having to remove the radio from your belt. It is compatible with Yaesu FT-7800, FT-8800, FT-8900, FT-1900 ,FT-1900R, FT-2900, FT-2900R, FT-1802, FT-1802M, FT-2800, FT-2800M. This is a non-OEM generic product.... |
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TYT TH-9000 60 Watt VHF Transceiver / 2 Meter Amateur Ham Radio 200ch $155.99 TYT TH9000 2M VHF amateur transceiver. ctcss/dcs/scan/dtmf. 200 AlphaNumeric Channels, Built In Emergency Alarm. Five P1-P5 Front Function keys are user prgrammable/function customizable. Includes Keypad mic, power cord & bracket. 136-174 Mhz. Requires 12Vdc at 14 Amp.... |
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TYT TH-9000 55 Watt 222Mhz Transceiver Amateur Ham Radio 200ch 220 Mhz $159.99 TYT TH9000 222Mhz VHF amateur transceiver. ctcss/dcs/scan/dtmf. 200 AlphaNumeric Channels, Built In Emergency Alarm. Five P1-P5 Front Function keys are user prgrammable/function customizable. Includes Keypad mic, power cord & bracket.Note: Mfgr's Photo Above shows 2M frequency (VHF version also available), - This Radio will be 222Mhz version, not 145Mhz.... |
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BlueTraks BT-211P 4.3-Inch Bluetooth Portable GPS Navigator $549.00 In dash hands-free Bluetooth and iPod system that integrates with the factory audio system. The BT-211P car kit features Bluetooth connectivity for most Bluetooth enabled cell phones to give you a great hands-free experience. After pairing, your cell phone will automatically sync-up with the BT211N, so you can leave it in your pocket, briefcase, or purse. You are able to make calls by voice dialin... |
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Kenwood TK-7160HK VHF Mobile Two Way Radio $533.00 The Kenwood TK-7160, models are engineered for VHF conventional operation, and are available in two power levels, including the high power model with 50 Watts output power. 160 Series mobiles have been designed to meet the mobile communications needs across many user markets, most notably school/public transportation, public service/safety, taxi/private transport, and general contracting/repair f... |
How is a land line telephone call made, and what are the transmitted signals involved ?
I know that when you pick up the handset and dial the desired number, the digits are transferred over the telephone lines using the DTMF system.
Now, lets say the 'destination' person picks up the receiver when he hears his telephone ringing .
What signal/s is/are sent to the dialing phone so that it knows that the other phone has been picked up ?
Also, in what way is our speech transferred over the phone ?
If i connected the output line of a walkman in series to the phone after the other person has picked up, will the message recorded on the walkman be heard on the line ?
Note that Im NOT holding the walkman speaker to the mic of the telephone.
If you could provide me with this technical knowledge or any a link to a site, i would be really grateful.
OK, this is complicated. When you lift the receiver, the phone company KNOWS you did this because the voltage applied to your telephone went DOWN. This change activates the "switch" which is what connects your phone to the rest of the system. As you dial, you cause links to be made in a vast chain which narrow down the possible endpoints by a factor of 10 for each number you dial. Finally, you narrow the possible endpoints to exactly one, at which time, the endpoint switch sends a ring signal to that one phone, which rings. The endpoint switch knows when the endpoint receiver is lifted in exactly the same way it knew YOU lifted yours. At that point, the switchs finally connect the path from your phone to the destination. The wires which connect the two carry analog signals just like any microphone is connected through an amplifier to speakers, except this is called full duplex, with signals going both ways at the same time. Inbetween, there can be analog to digital converters which digitize the analog signal from your mouthpiece and transferred digitally from here to there and then at the destination, a digital to analog converter makes it back into an analog signal which ends up at the earpiece so you hear sound. AS to you connecting things to the phone line, there are special devices to allow you to do this. Visit an electronics store and buy a proper interface. You can do damage to your device or worse the devices at the phone company if you connect things to the wire that are not designed to be an interface. Damage to the phone company equipment will be really, REALLY expensive. On your phone bill, you are specifically prohibited from connecting a non-phone company approved device to the wire. Playback using the speaker into the microphone. The quality may be poor, but you stand NO risk of damage if you simply use the SOUND from your player in the same manner as your VOICE.