Christopher Williamson was jailed for six months over the "bizarre behaviour" in Wakefield city centre on October 2 this year.
Leeds Crown Court heard Williamson approached members of the public and waved a cutlery knife in front of them.
Jade Edwards, prosecuting, said one man was with his baby and toddler when he was approached by the defendant and he feared for the safety of his family.
Police were contacted and officers arrested Williamson.
He was searched and a knife and fork were found in his pocket.
Williamson, of Montague Street, Agbrigg, Wakefield, pleaded guilty to possession of a blade in public.
He has a previous conviction for possessing a knife in public, meaning he must receive a minimum prison sentence of six months.
The 47-year-old also has convictions for making threats to kill, possessing an imitation firearm and criminal damage.
The defendant had been released from custody a week before his latest offence.
Williamson appeared in court without legal representation.
When asked by the judge, Recorder Ben Nolan QC, if he wished to see a solicitor, Williamson replied: "I would just like to get sentenced and get it out of the way."
The court heard Williamson has mental health issues which are made worse by his long-standing addiction to amphetamines.
Probation officer Phil Brown said Williamson had said in an interview that he had committed the offence after relapsing into drug use soon after being released from custody.
The officer said: "He was paranoid that he was seeing malevolent forces that were out to do him harm.
"He decided to take the knife out into the street and wave it in front of his watch because he thought it had a camera in it fitted by the police.
"He said he thought if he waved the knife in front of the watch the police would see it and come and arrest him."
Mr Brown said Williamson had stated that he was sorry if he had frightened members of the public by his actions.
Sentencing, Recorder Nolan told Williamson: "Your addiction to amphetamines led to your bizarre behaviour. You need to address it.
"I do hope that you take whatever help is available.
"I am probably being lenient but, under the circumstances, I think six months is enough for now."