*Question G8C08:
Which of the following statements is true about PSK31?*  

*Correct Answer is  B: Upper case letters use longer Varicode bit sequences and thus slow down transmission*  

### AI Response: (may contain errors)  

PSK31 is a digital mode used in amateur radio that is known for its efficiency and low bandwidth usage. Let's break down the choices:

1. **Correct Answer: B - Upper case letters use longer Varicode bit sequences and thus slow down transmission**

   - **Explanation**: PSK31 uses a type of encoding called Varicode, where each character is represented by a unique sequence of bits. In Varicode, upper case letters generally have longer bit sequences compared to lower case letters. This means that when you send upper case letters, it takes more time to transmit them, effectively slowing down the transmission rate.

2. **Why the other choices are incorrect:**

   - **Choice A: Upper case letters are sent with more power**
     - **Explanation**: PSK31 does not change the power level based on the character being sent. The power remains constant regardless of whether the character is upper or lower case.

   - **Choice C: Error correction is used to ensure accurate message reception**
     - **Explanation**: PSK31 does not inherently include error correction. It relies on the robustness of the modulation and the operator's ability to correct errors manually if needed.

   - **Choice D: Higher power is needed as compared to RTTY for similar error rates**
     - **Explanation**: PSK31 is actually more efficient than RTTY in terms of power usage. It typically requires less power to achieve similar error rates due to its narrow bandwidth and phase shift keying technique.

In summary, the correct answer is B because the Varicode used in PSK31 results in longer bit sequences for upper case letters, which slows down the transmission. The other choices are incorrect because they either misrepresent how PSK31 operates or compare it inaccurately to other modes.