Global System for Mobile Communications (GSM) phones raise expectations among professional-mobile-radio users to levels that system makers are only now beginning to address. Not long ago, you’d need to be a member of the emergency services or a top executive to make calls from a mobile phone. Now, anyone with $100 to spend can roam most of Europe and enjoy direct access to international communications networks. Consumer models have a lot in common with professional user needs, but there are still compelling reasons why GSM can’t deliver in the professional user market. With dedicated professional-mobile-radio backgrounds, alternative systems compete for private-mobile-radio (PMR) and public-access mobile-radio (PAMR) deployments. Now, professional users can enjoy cellular like telephony and private radio dispatcher services with the same mobile handset. Read the rest of this entry »

Analog-circuit designs have fundamentally different architectures from those of processor, FPGA, and PLD designs. Once you implement the circuit topology and parameters, the circuit’s signal-processing function is relatively fixed. Sure, some functional blocks exist, such as filters, in which you can digitally adjust cutoff frequency, roll-off, and other factors by varying the clock (for switched-capacitor designs) or adjusting circuit factors via DACs, but these examples are the exceptions. Most designs are fixed in their functions and nearly fixed in their performance. Read the rest of this entry »