(A). The primary purpose of a speech processor as used in modern transceivers is to increase the intelligibility of transmitted phone signals during poor conditions. The speech processor brings up the power of low level parts of phone or voice signals while not changing the high level parts of the signal. This effectively brings up the average signal power to a more even and understandable level, but with the benefit of not increasing the peak envelope power.

Last edited by N8GCU. Register to edit

Tags: arrl chapter 5 arrl module 19

The speech processor affects transmitted phone signals such as single sideband, by increasing the average power. The processor increases the power of low level signals, but not those of higher level signals. This raises the average signal level and makes the communication more intelligible. Another benefit of using the speech processor is that it raises the average power in such a way that the Peak Envelope Power is not increased.

Processing even SSB Speech "Increases average power" of all speech.

Last edited by hauckrealty. Register to edit

Tags: arrl chapter 5 arrl module 19

(D). All of the choices listed are correct as results of an incorrectly adjusted speech processor. A speech processor modifies the signal by increasing the lower power parts of the signal to a higher average level without raising the upper level tones. Over or under adjusting this processor can cause various forms of distortion. It can bring up low level background noise (such as fans, background voices, machine noises) along with the low end range of your voice signal. Overprocessing can also distort your speech or overdrive the transmitter output causing "splatter" signals

If you incorrectly adjust some speech then "ALL" speech gets messed up.

Last edited by hauckrealty. Register to edit

Tags: arrl chapter 5 arrl module 19

(C). An S meter measures received signal strength.

The signal strength measurements are related to the "S" or "strength" part of the RST code for reporting signal quality. The scale uses S units on a subjective scale of S1 to S9 (see RST Code). The meter is not always accurately calibrated, but it tries to make the S reading less subjective by relating it to a logarithmic scale of decibel units.

A change of one S unit indicates a four times increase or decrease in signal power, this corresponds to a 6 decibel change.

Note: For more info see Wikipedia: S meter, RST code

Some common decibel values and their corresponding change in power

Hint: S stands for “Signal Strength”

Last edited by mpainter1986. Register to edit

Tags: arrl chapter 5 arrl module 20

An S meter reading of 20 dB over S9 is 100 times stronger than an S9 signal, assuming a properly calibrated S meter.

The S meter measures the signal strength by trying to relate the subjective S1-S9 scale with a logarithmic scale of decibel units, which is a powers of 10 scale. From S1 through S9, a one unit change in S unit corresponds to a 4 fold increase in power which is a change of 6 dB on the logarithmic scale.

Above S9 the scale continues as 10 decibel units over S9. Following the logarithmic scale,
\(10\text{ dB}\) over S9 is 10 \((10^1)\) times stronger,
\(20\text{ dB}\) over S9 is 100 \((10^2)\) times stronger.

Also remember every \(3\text{ dB}\) is \(\approx 2\times\) power, so
\(20\text{ dB}\) is between 6 and 7 doublings.
\(\frac{ 20 }{ 3} \approx 6.66\), which we can confirm with:
\(2^{6.66} = 101\)

For more info see Wikipedia: S meter, RST Scale, Decibel

Silly hint: S(9) x S(9) = S(81) 81 + 20 dB = 101 101 is closest to the answer.

Last edited by kt4obx. Register to edit

Tags: arrl chapter 5 arrl module 20

An S meter (signal strength meter) is found in a receiver or transceiver. The scale markings are derived from a system of reporting signal strength from S1 to S9 as part of the R-S-T system. The term S unit can be used to refer to the amount of signal strength required to move an S meter indication from one marking to the next.

For more info see Wikipedia: S meter, R-S-T system

Last edited by jeff00seattle. Register to edit

Tags: arrl chapter 5 arrl module 20

The power output of a transmitter must be raised approximately 4 times to change the S-meter reading on a distant receiver from S8 to S9. Thus for the reading on the scale to increase by 1 S unit indicates that the signal strength has increased by four times, which corresponds to approximately a change of 6 decibels on a logarithmic scale.

For more info see Wikipedia: S meter, RST Code

A mnemonic - An S-meter Steps by Six db (which is a 4x change)

Last edited by liewo. Register to edit

Tags: arrl chapter 5 arrl module 20

The bandwidth from 7.175 to 7.178 MHz is the frequency range occupied by a 3 kHz LSB signal when the displayed carrier frequency is set to 7.178 MHz. Most radios show the frequency of a single sideband transmission as the frequency of the carrier signal. An SSB signal with a bandwidth of 3 kHz using the lower sideband (LSB) would be the range from 3 KHz below the carrier frequency up to the carrier frequency. In the same manner, the same signal using the upper sideband (USB) would use the range from the carrier frequency to 3 KHz above the carrier frequency.

Easy Hint: LOWER sideband goes DOWN, and the correct answer is the only answer that ends in 7.178 MHz.

Last edited by kf0jfq. Register to edit

Tags: arrl chapter 5 arrl module 19

A USB signal with a bandwidth of \(3\ \text{kHz}\) displayed at a frequency of \(14.347\ \text{MHz}\), uses the range from the \(14.347\ \text{MHz}\) to \(14.350\ \text{MHz}\).

Most radios show the frequency of an SSB transmission as the frequency of the signal carrier. An upper sideband bandwidth ranges from the carrier frequency level for the range of 1 bandwidth above that number:

When adding frequencies together, make sure both frequencies are using the same units:

\begin{align} Range &= \small (14.347\ \text{MHz}\ to\ 14.347\ \text{MHz} + 3\ \text{kHz})\\ &= \small (14.347\ \text{MHz}\ to\ 14.347\ \text{MHz} + 0.003\ \text{MHz})\\ &= \small (14.347\ \text{MHz}\ to\ 14.350\ \text{MHz}) \end{align}

Last edited by gavin williams. Register to edit

Tags: arrl chapter 5 arrl module 19

(A). A 3 kHz wide LSB signal on the 40 meter General Class phone segment should have a displayed carrier frequency no closer than 3 kHz above the lower edge of the segment. A lower sideband (LSB) transmission uses the width of the band BELOW the displayed frequency. An amateur operator must take care that the entire portion of the transmitted signal is within granted class privileges. You cannot have an LSB signal with a displayed frequency at exactly the lower edge, because the LSB transmission would actually be outside the permitted range! You must keep the displayed frequency at least 1 bandwidth from the edge of the band segment.

Last edited by woglesby. Register to edit

Tags: arrl chapter 5 arrl module 19

When using a 3 kHz wide USB signal, your displayed carrier frequency should be no closer than 3 kHz below the upper edge of the band. An upper sideband transmission actually uses the frequency portion from the carrier frequency to 1 bandwidth ABOVE that frequency. An amateur operator must make sure that the entire signal is within the band privileges. To keep a 3 KHz USB signal within range, a carrier frequency of no closer than the bandwidth below the upper range may be used.

Last edited by liewo. Register to edit

Tags: arrl chapter 5 arrl module 19