decreasing BTC rewards / round

[LuckyDime]

Hello all,

I've started mining bitcoins with one USB Asic miner in october 2013, a round reward was 0.00001xxx-0.00003xxx, then in november I've installed a second one and the round reward increased to 0.00003xxx-0.00008xxx. But from end of  november, the round reward dropped again between 0.00001xxx and 0.00003xxx. The hash rate still ~670Mhash (2x333Mhash). Is it normal?
I've also found, that in october-november a round took 0,5-1,5 hour and the number of it was 10-20 / day. Nowadays the number of rounds are 3-6 / days, and often they tooks 4-11 hours long. Is also normal?

[marianna]

The Bitcoin network difficulty increases over time, so you get less reward for the same hash power.

[Fckbankscoin]

Bitcoin difficulty changes every 2 weeks, the rounds a day is depending on the network hashrate and adjusts the difficulty in such a manner that the amount of coins generated increases at an (almost) lineair rate.

[LuckyDime]

In that case If I want to keep the level of BTC reward I have to invest new hardware time-after-time?
Could the rate of BTC / number of BTC transaction modify the long of a round /number of round in a day?

[nerobie]

i hash rate about at 666Mhash (2x333Mhash) and it's normal

[BlockChainLottery]

In that case If I want to keep the level of BTC reward I have to invest new hardware time-after-time?
Could the rate of BTC / number of BTC transaction modify the long of a round /number of round in a day?

First one yes, second one no. Number of transactions has nothing to do with the hash rate.

[LuckyDime]

Number of transactions has nothing to do with the hash rate.

I mean the number of rounds and the lenght of it. If I know well, transactions also checked by miners.

[BlockChainLottery]

Number of transactions has nothing to do with the hash rate.

I mean the number of rounds and the lenght of it. If I know well, transactions also checked by miners.

No.