What is a VLF transmitter?
Very Low Frequency (VLF) communications transmitters use digital signals to communicate with submerged submarines on at frequencies of 3-30 kHz. The eighteen Trident submarines constitute about half the US strategic nuclear capability.
How far can VLF transmit?
Since VLF waves can penetrate at least 40 meters (131 ft) into saltwater, they are used for military communication with submarines….Very low frequency.
| Frequency range | 3–30 kHz |
|---|---|
| Wavelength range | 100-10 km |
What is VLF used for?
Techopedia Explains Very Low Frequency (VLF) Very low frequency signals have large wavelengths that allow them to diffract around large obstacles, propagate as ground waves along the earth’s curvature and penetrate salt water, which is why they have been used by the military for communicating with submarines.
What is the VLF range?
VLF electromagnetic technology is used in the frequency range of 15–30 kHz.
How does VLF testing work?
VLF testing is a withstand test usually carried out at a frequency of between 0.1 Hz and 0.01 Hz rather than 50/60 Hz. The test is conducted on entire drum of cable rather than a test sample length. Although the frequency is very low, it is an alternating current with polarity reversals every half cycle.
What is VLF and ELF waves?
ELF/VLF stands for Extremely Low Frequency and Very Low Frequency, and refers to the range 300 Hz to 30 kHz. We’re talking about radio waves, like the AM/FM signals you get, just at an even lower frequency.
What is a VLF survey?
Very-low-frequency (VLF) Methods VLF survey methods use very-low-frequency, radio communication signals to determine electrical properties of shallow bedrock and near-surface soils, primarily as a reconnaissance tool.
Why VLF test is done?
Very Low Frequency testing for Medium Voltage and High Voltage cables is a method for verifying the integrity of the cable insulation. VLF testing is a withstand test usually carried out at a frequency of between 0.1 Hz and 0.01 Hz rather than 50/60 Hz.
How does a VLF tester work?
VLF operation reduces the power required to load cables which present a capacitive load. Test sets typically operate at 0.1Hz. The length of cable that can be tested at a given power increases by a factor of 5,000 compared to 50Hz with consequent weight and cost savings.
Is VLF test destructive?
Is the VLF test destructive? VLF hipoting is not destructive to good insulation and does not lead to premature failures like DC voltage testing. Using VLF does not cause degradation of good insulation nor aggravate defects too small to be triggered into PD under the test voltage.
What is the difference between VLF and hipot?
High potential (hipot) cable system testing can be performed using DC, AC or Very Low Frequency AC (also known as VLF) test voltage. Such testing can be conducted as an acceptance test for new installations or as a maintenance test for existing installations.