Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency (HF), and the next higher frequencies are known as Ultra high frequency (UHF). The frequency allocation is done by ITU. Common uses for VHF are FM radio broadcast, television broadcast, land mobile stations (emergency, business, and military), long range data communication with radio modems, Amateur Radio, marine communications, air traffic control communications and air navigation systems (e.g. VOR, DME & ILS).
It is considered that one of the most significant events in the history of broadcast television regulation was the creation of an artificial scarcity of VHF licenses. The FCC's decision to locate television service on the limited VHF band changed the ways of television service and network competition in the industry. The rationale of this policy was to create a situation of increased competition and viewer choice.
Television was added to the VHF band in 1941 on channels one through six. During the war freeze, channel one was removed and used only for war purposes. Later, in 1945, channels seven through thirteen were added.
Marine VHF radio is installed on all large ships and most seagoing small craft. It is used for a wide variety of purposes, including summoning rescue services and communicating with harbours, locks, bridges and marinas, and operates in the VHF frequency range, between 156 to 174 MHz.
Although it is widely used for collision avoidance, its use for this purpose is contentious and is strongly discouraged by some countries, including the UK. VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice (if equipped), and navigation signal. The identifier is morse code. The voice signal is usually station name, in-flight recorded advisories, or live flight service broadcasts.
A High-Efficiency 400 Watt 13.56 MHz RF Power Amplifier
This paper details the design, development, assembly and performance of a low cost, high efficiency, 400Watt, 13.56MHz RF power amplifier (PA) operated from a 100VDC supply and with an efficiency of 75%. The PA is built around a Symmetric Pair of low cost RF power MOSFETs from Advanced Power Technology (APT). The transistors are from a new generation of high quality, commercial, HF/VHF, silicon, 300V RF power MOSFETs in TO-247 plastic packages...
Views: 1593 | Votes: 18 | Comments: 0 | Rating: 2 | Rank: 3 | Added: Mar 24, 2013 |
Field Strength Meter
This is a wide band signal strength meter circuit which responds to small changes in RF energy, designed to be used for the VHF spectrum and will respond to AM or FM modulation or just a plain carrier wave. This circuit measures radio field strength by converting the signal to DC and amplifying it. This field strength meter was designed for VHF frequencies in the range 80 -110 MHz.The inductor L1 is 4 to 6 turns of 20swg wire air spaced wound on a quarter inch former or.....
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Video to RF Signal Conveter
This circuit is a RF modulator which can be used for modulating of video signals. The P1 controls the Light and the P2 controls the contrast of video signal. The RF modulated output signal can be received on the VHF band ( about 189 MHz ). Note that the circuit don't modulate the audio signal of the pictures. ..
Views: 2858 | Votes: 48 | Comments: 0 | Rating: 1 | Rank: 0 | Added: Feb 16, 2013 |
wireless FM bug
This project is a miniature, VHF FM (wideband) Wireless Microphone transmitter of the type that are commonly refered to as BUG's. Note that "BUGS" are illegal but "Wide-Band Frequency Modulation Wireless Microphones" (WBFMWMs) are not, as so many people have told me (including the RSGB!). Besides, the AF sensitivity of this transmitter prevents it from being an effective bug for eaves-dropping! I personally use one of these WBFMWMs plugged into my HF rig headphone socket.....
Views: 684 | Votes: 58 | Comments: 0 | Rating: 8 | Rank: 0 | Added: Feb 7, 2013 |
VHF Audio/Video Sender
The circuit presented here is a simple audio/video transmitter with a range of 3 to 5 metres. The A/V signal source for the circuit may be a VCR, a satellite receiver or a video game etc. A mixer which also operates as an oscillator at VHF (H) channel 5 TV frequency is amplitude modulated by video signal and mixed with frequency mo enna, contains video carrier frequency of 175.25 Mhz and audio carrier frequency of 180.75 Mhz. Then, the transmitter is a B-System of CCIR.....
Views: 1971 | Votes: 13 | Comments: 0 | Rating: 9 | Rank: 0 | Added: Jan 2, 2013 |
VHF - UHF band reciever
Here is a nice little receiver for narrow-band FM reception. It can also be used to receive FSK, RTTY and PACKET signals from the HF bands. Basic receiver sensitivity is in the region of 1uV PD and the receiver can be tuned to almost any frequency from 100KHz up to probably 120MHz. It is a bit big and cramped, but I think you will have no difficulties reading it. The receiver is built on a single- sided PCB, which is quite unusual for this type of circuit. I do have a PCB.....
Views: 3799 | Votes: 26 | Comments: 0 | Rating: 6 | Rank: 0 | Added: Dec 31, 2012 |
Universal frequency meter
This is 7-digit frequency meter measuring frequency from 10 Hz up to 1300 MHz. It is based on ideas of PIC16F84 based frequency meter. The measuring range is divided into two subranges: 10Hz - 25MHz and 25 MHz - 1300MHz. The decimal point is after MHz digit, but can be set at any position...
Views: 1725 | Votes: 44 | Comments: 0 | Rating: 9 | Rank: 0 | Added: Dec 16, 2012 |
Simple Field Strength Meter
This Field Strength Meter is simple and also quite sensitive. It uses an ordinary digital voltmeter to measure RF signal strength up to a few hundred MHz. The multimeter should be set to the lowest dc volts range for maximum sensitivity. This is normally 200mV DC for most meters. The circuit works well at VHF (around 100MHz) and was quite pleased with the results. L1 was 7 turns on a quarter inch former with ferrite slug...
Views: 1718 | Votes: 28 | Comments: 0 | Rating: 4 | Rank: 0 | Added: Dec 9, 2012 |
VHF TV Signal Amplifier
Many times we needed to strengthen a small signal in the region of VHF or FM. The preamplifier that to you we propose offers 20dB in all the region of VHF and it still can reach also their 500MHZ. The amplifier is a circuit of high frequency RF with distinguishable materials. The amplifier as circuit strengthens the tendency of signal with concrete aid, depending on the frequency of signal...
Views: 4411 | Votes: 108 | Comments: 0 | Rating: 9 | Rank: 0 | Added: Nov 21, 2012 |
VHF remote control
A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here.
The miniature transmitter module shown in Fig. 1, which just measures 34 mm x 29 mm x 10 mm, can be used to operate all remote control receiver-cum-switch combinations described in this project. A compact 9-volt PP3 battery can be used with the transmitter. It can transmit signals up to 15 metres without any aerial. The operating frequency of the transmitter is 300 MHz......
Views: 98 | Votes: 83 | Comments: 0 | Rating: 5 | Rank: 0 | Added: Oct 17, 2012 |
Single frequency oscillator,vhf range, 0.1hz precision The Projects Forum.
VHF UHF Low-Noise amplifiers circuit can be designed using the MAX2664 and MAX2665 ultra-compact LNAs for VHF UHF applications.These devices incorporate a broadband LNA with an integrated bypass sw...
The 30 watt amplifier circuit shown below provides an appropriate power boost with an input of 4 watt up to 6 watts. The circuit is designed to cover 88-108MHz FM Broadcast Band. However, the circu...
I need to make an oscillator that generates a very specific frequency, in the vhf range (let's say for example 192,353,452.3hz), accurate -and stable- down to the last digit. That is with a resolut...
I am in the midst of rewiring all of the house circuits in my boat. I have a six switch panel, so I mounted a bus bar, and would like to use that to.
This is a simple and low cost wide band VHF field strength meter. The field strength is measured by converting the radio signal to DC and measuring it. The RF signal will be picked up by the coil a...