If the digital data rate of 9600 bps is encoded using 8-level phase shift keying (PSK) method, what is the modulation rate?
Understand the Problem
The question is asking us to calculate the modulation rate based on the given digital data rate and the method of encoding used, which is 8-level phase shift keying (PSK). We need to determine how many symbols are required to represent the data rate using the PSK method.
Answer
$$ R_s = \frac{R_d}{3} $$
Answer for screen readers
The modulation rate is given by the formula:
$$ R_s = \frac{R_d}{3} $$
Where $R_d$ is the digital data rate.
Steps to Solve
- Identify the given information
The digital data rate is the value that needs to be defined, let's denote it as $R_d$. For 8-level PSK, we know that each symbol can represent 3 bits, because $2^3 = 8$.
- Determine the number of symbols needed
We can find the number of symbols required to represent the data rate by dividing the digital data rate by the bits per symbol. The formula is:
$$ N_s = \frac{R_d}{b} $$
Where:
- $N_s$ is the number of symbols
- $b$ is the number of bits per symbol, which is 3 for 8-level PSK.
- Calculating the modulation rate
Next, we can find the modulation rate, which is the rate at which symbols are transmitted. The modulation rate (or symbol rate) can be calculated as:
$$ R_s = N_s $$
Thus, substituting our earlier equation:
$$ R_s = \frac{R_d}{b} $$
Replace $b$ with 3 for 8-level PSK:
$$ R_s = \frac{R_d}{3} $$
- Final calculation
Now you can substitute the actual value of the digital data rate $R_d$ into the formula to get the modulation rate.
The modulation rate is given by the formula:
$$ R_s = \frac{R_d}{3} $$
Where $R_d$ is the digital data rate.
More Information
In 8-level PSK, each symbol represents 3 bits of information, which allows for a higher data rate compared to simpler modulation methods. Understanding modulation techniques is crucial for efficient data transmission in communication systems.
Tips
- Confusing the number of bits per symbol with the number of levels. Remember that for 8-level PSK, $3$ bits are represented per symbol.
- Forgetting to substitute the actual data rate into the final formula can lead to incomplete answers.
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