Switch on your satellite television receiver in Tehran nowadays and something is amiss -- "No Signal," the otherwise fuzzy television screen says for much of the day and night.
With presidential elections just over a week away, Islamic Iran's technological guardians appear to be waging a war against enemies in the airwaves -- opposition-run television channels.
The problem, however, is that they may also be frying people's brains.
"Microwaves," explained an Iranian satellite television technician, who earns his keep by installing dishes even though they are technically banned.
"They're jamming, and these signals used to block the satellites have never been so strong," said the dish man, who for obvious reasons preferred that he not be named.
Since Iran's Islamic revolution 26 years ago, the regime has been fighting off what it calls "Westoxication." But in recent years satellite dishes have mushroomed across the rooftops of the sprawling, smog-ridden capital.
Police and militiamen launch occasional crackdowns, but it is a losing battle. So instead they appear to be throwing out noise -- blocking out 20 or so opposition channels and their mix of heretical anti-regime chatter and saucy Persian pop videos.
"Day and night, the opposition radio and television stations keep calling on our people to boycott the election," fumed Ayatollah Mohammad Emami Kashani, a top cleric, in his Friday prayer sermon last week.
Eager to prevent a boycott of the polls -- and therefore more questions being raised over how the ruling clergy mix Islam and democracy -- the jamming effort appears to be unprecedented.
"It's as if they found a huge microwave oven, opened the door and switched it on. The microwaves are going out day and night," the technician said.
"The signals are so powerful that even other channels using the Telestar 12 satellite have been blocked in some areas of Tehran," he added.
Experts believe that while Iran may be unable to totally block the signals, they can beam so much noise over the city's grey-brown skyline that broadcasts suffer lengthy drop-outs.
The main targets are around six channels run by sympathizers of the ousted monarchy. These stations, mostly based in Los Angeles, spend their time trying to convince Iranians that the rule of the late shah, Mohammad Reza Pahlavi, was a golden age, and that Islamic Iran isn't.
Other channels teasing the turbans include the MTV-inspired Persian Music Channel, which shows far too much flesh for the regime's liking.
But there are also possible side effects of the battle of the frequencies.
The local signals of state television, busy trying to drum up interest in the elections, have also suffered. The mobile telephone network, already subject to overcrowding and poor service, is another apparent victim, given that the coverage zone has reportedly shrunk in parts of the capital.
When reports of the jamming effort emerged two years ago in the Iranian press, the Ministry of Post, Telegraphs and Telephones (PTT) -- technically in charge of frequency space -- pleaded innocence.
The World Health Organization (WHO) also cautioned that such microwave frequencies could "induce heating in body tissues which may provoke various physiological and thermoregulatory responses, including a decreased ability to perform mental or physical tasks as body temperature increases."