PENGUNTUKAN KELAS BAGI PERANTI

PERKHIDMATAN RADIO PERIBADI

1. Takrif

(1) Dalam penguntukan kelas ini, “peranti perkhidmatan radio peribadi” ertinya suatu peranti radiokomunikasi dua hala yang dikendalikan dalam jalur frekuensi yang ditetapkan.

(2) Tertakluk kepada subperenggan (1), semua istilah yang semata-mata bersifat teknik hendaklah mempunyai erti yang sama seperti dalam Konvensyen Telekomunikasi Antarabangsa.

2. Jalur frekuensi

Suatu peranti perkhidmatan radio peribadi hendaklah hanya menggunakan mana-mana jalur frekuensi yang berikut yang telah diuntukkan bagi penguntukan kelas ini, antara penggunaan lain, atas dasar perkongsian tidak eksklusif:

(a) 26.9650 MHz hingga 27.4050 MHz;
(b) 477.0125 MHz hingga 477.4875 MHz; atau
(c) 477.5250 MHz hingga 477.9875 MHz.

3. Penguntukan kelas

Penguntukan kelas ini memberikan hak kepada mana-mana orang untuk mengendalikan suatu peranti perkhidmatan radio peribadi tertakluk kepada:

(a) syarat-syarat sebagaimana yang dinyatakan dalam perenggan 4; dan
(b) peranti itu dikendalikan dalam jalur frekuensi sebagaimana yang dinyatakan dalam ruang kedua Susunan B, C dan D.

4. Syarat-syarat

(1) Rancangan saluran

Rancangan saluran sebagaimana yang dinyatakan dalam Susunan B, C dan D hendaklah dipatuhi.

(2) Jenis modulasi dan ruangan saluran

(a) Jenis modulasi hendaklah sebagaimana yang dinyatakan dalam ruang ketiga Susunan B, C dan D; dan
(b) Ruangan sa1uran hendaklah sebagaimana yang dinyatakan dalam -

(i) ruang kecil pertama dan kedua ruang kelima Susunan B; dan
(ii) ruang kelima Susunan C dan D.

(3) Saluran simpanan

Saluran sebagaimana yang dinyatakan dalam ruang keenam Susunan B, C dan D hendaklah disimpan bagi kegunaan kecemasan dan kegunaan panggilan.

 

 

 

IT’S WHAT YOU HAVE AND WHAT YOU DO WITH IT

Lowpass filters are primarily a passive device used in the transmission and reception of radio signals in the BF frequency range (3-30 Mhz). Their intended purpose is to prevent the radiation of signals above 30 Mhz. that often emanate from transmitters due to the mixing of various signals in the transmitter’s internal circuitry. The filters should be thought of as a frequency-selective bypass device. ‘Mat is,- the unit will pass -through without attenuation (loss) those transmitted and received signals below 30 Mhz and short circuit (between coaxial line center conductor and outer shield conductor) those signal products whose frequency is above 30 Mhz.

The point at which the loss through the filter is measured as -3db (half of the power lost) is called the cutoff frequency. Above this point as frequency increases attenuation also increases, usually at a rate of rapid ascent. Lowpass filters in receiving operations work the same way. They prevent the reception of frequencies above 30 Mhz. which, generated locally by broadcasters can frequently disturb HF reception.

Many filters produced over the past 30 years or so have been either poor by design or installed by the user in such a way that the filter’s ability to work was compromised, or both. The result was the expense of a lowpass filter that did not contribute to enhanced station ability or reduction of interference.

HELPFUL HINTS AND SUGGESTIONS TECHNICAL

With the increasing popularity of complex and computer-aided home telephone units manufactured by numerous companies worldwide comes a corresponding increase in both the quantity and severity of telephone interference caused by local radio broadcast transmitters. The new telephones, both domestic and imported, are the most susceptible and delicate ever built, and few manufacturers of the devices have given much consideration or effort to designs which include resistance to RFI and other forms of electromagnetic interference.

Making matters worse is the fact that ground terminal connections for telephones are rarely available at the location of an extension telephone, and telephone wiring is all unshielded and exposed.

Telephone interference is caused by radio signals produced in the immediate vicinity that are intercepted by the mass of telephone wiring in the home and outside on telephone company elevated wiring. Signals enter the phone on different conductors, working their way through phone circuits and causing current flow, resulting in voice distortion or noise.

Most telephone interference can be remedied by the simple installation of a telephone filter that plugs simply into the rear of the phone. These devices are designed to insert a choking effect, or loss at radio frequencies, into the phone wiring. They have no effect on the telephone operation. About the only realistic way to resolve phone interference short of making internal circuitry changes to the phone is by choking the RF signals before they enter.

Antenna

An antenna is a device that transmits and/or receives electromagnetic waves. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned to the same frequency band that the radio system to which it is connected operates in, otherwise reception and/or transmission will be impaired.

Wavelength

We often refer to antenna size relative to wavelength. For example: a half-wave dipole, which is approximately a half-wavelength long. Wavelength is the distance a radio wave will travel during one cycle. The formula for wavelength is:

Note: The length of a half-wave dipole is slightly less than a half-wavelength due to end effect. The speed of propagation in coaxial cable is slower than in air, so the wavelength in the cable is shorter. The velocity of propagation of electromagnetic waves in coax is usually given as a percentage of free space velocity, and is different for different types of coax.

RSN Certificate

 

QSL Card